Grace is a WYSIWYG tool to make two-dimensional plots of scientific data. It runs under various (if not all) flavors of Unix with X11 and M*tif (LessTif or Motif). It also runs under VMS, OS/2, and Windows (95/98/NT/XP). Its capabilities are roughly similar to GUI-based programs like Sigmaplot or Microcal Origin plus script-based tools like Gnuplot or Genplot. Its strength lies in the fact that it combines the convenience of a graphical user interface with the power of a scripting language which enables it to do sophisticated calculations or perform automated tasks.
Grace is derived from Xmgr (a.k.a. ACE/gr), originally written by Paul Turner.
From version number 4.00, the development was taken over by a team of volunteers under the coordination of Evgeny Stambulchik. You can get the newest information about Grace and download the latest version at the Grace home page.
When its copyright was changed to GPL, the name was changed to Grace, which stands for ``GRaphing, Advanced Computation and Exploration of data'' or ``Grace Revamps ACE/gr''. The first version of Grace available is named 5.0.0, while the last public version of Xmgr has the version number 4.1.2. Paul still maintains and develops a non-public version of Xmgr for internal use.
As of now, most of the codebase has been re-written from scratch.
Copyright (©) 1991-1995 Paul J Turner, Portland, OR
Copyright (©) 1996-2004 Grace Development Team
Maintained by Evgeny Stambulchik
All Rights Reserved
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
For certain libraries required to build Grace (which are therefore even included in a suitable version) there may be different Copyright/License statements. Though their License may by chance match the one used for Grace, the Grace Copyright holders can not influence or change them.
Package | License |
Cephes library | Free |
T1lib | LGPL |
Expat | MIT/X |
Xbae | BSD-like |
Tab Widget | BSD-like |
ListTree Widget | LGPL |
yacc
or,
better, bison
)./usr/local/src/grace-x.y.z
and the compilation
will be performed in /tmp/grace-obj
, do the following:
% mkdir /tmp/grace-obj % cd /tmp/grace-obj % /usr/local/src/grace-x.y.z/ac-tools/shtool mkshadow \ /usr/local/src/grace-x.y.z .
configure
shell script attempts to guess correct
values for various system-dependent variables used during
compilation. It uses those values to create Make.conf
in the
top directory of the package. It also create config.h
file
containing system-dependent definitions. Finally, it creates a shell
script config.status
that you can run in the future to
recreate the current configuration, a file config.cache
that
saves the results of its tests to speed up reconfiguring, and a file
config.log
containing compiler output (useful mainly for
debugging configure
). If at some point config.cache
contains results you don't want to keep, you may remove or edit it../configure --help
to get list of additional switches specific to Grace./configure <options>
. Just an example:
% ./configure --enable-grace-home=/opt/grace --with-extra-incpath=/usr/local/include:/opt/include \ --with-extra-ldpath=/usr/local/lib:/opt/lib --prefix=/usrwould use
/usr/local/include
and
/opt/include
in addition to the default include path
and /usr/local/lib
and /opt/lib
in addition
to the default ld path. As well, all stuff would be put under
the /opt/grace directory and soft links made to
/usr/bin
, /usr/lib
and /usr/include
.
Note: If you change one of the
--with-extra-incpath
or
--with-extra-ldpath
options from one run of
configure to another, remember to delete the
config.cache
file!!!make
If something goes wrong, try to see if the problem has been
described already in the Grace FAQ (in the doc
directory).make tests
This will give you a slide show demonstrating some nice
features of Grace.make install
make links
The later (optional) step will make soft links from some files
under the Grace home directory to the system-wide default
locations (can be changed by the --prefix
option
during the configuration, see above).We neither provide nor support binary builds. Please contact your vendor. Practically all general-purpose GNU/Linux and other Open Source distributions have a Grace package in either main or contributed sections.
For a jump-in start, you can browse the demos ("Help/Examples" menu tree). These are ordinary Grace projects, so you can play with them and modify them.
O.k. Here's a VERY quick introduction:
A plot in Grace is built in a tree-like manner (reflected 1:1 in the Explorer tool) out of "Quarks". Quark is an object that may have its own presentation properties plus a number of children quarks.
Some quarks impose a coordinate transform; these are "Project", "Frame", and "Graph". Correspondly, there are three types of coordinates in Grace: the viewport, the frame, and the world coordinates. A child position is always defined in the coordinate frame of its parent, so e.g. points of data sets are defined in the graph's world coordinates. The frame coordinates go from 0 to 1 in both X and Y dimensions of a Frame.
The viewport coordinates correspond to the image of the plot drawn on the canvas (or printed on, say, PS output page). Actually, there is yet another level in the hierarchy of coordinates - the device coordinates. However, you (as a user of Grace) should not worry about the latter. The mapping between the viewport coordinates and the device coordinates is always set in such a way that the origin of the viewport corresponds to the left bottom corner of the device page, the smallest of the device dimensions corresponds to one unit in the viewport coordinates. Oh, and the most important thing about the viewport -> device transformation is that it is homotetic, i.e. a square is guaranteed to remain a square, not a rectangle, a circle remains a circle (not an ellipse) etc.
The transformation converting the world coordinates into the frame and further into the viewport ones is determined by both the graph type and the axis scaling.
Frame is a rectangular placeholder for one or more graphs (if there are more than one graph in a frame, such graphs are called overlaid), and optional annotating objects (texts, boxes, etc). As well, Frame is responsible for displaying legend box holding legend entries for its all children graphs.
A graph may hold (every element is optional) Axes, Sets, and additional annotative objects.
A set is a way of representing datasets. It consists of a pointer to a dataset plus a collection of parameters describing the visual appearance of the data (like color, line dash pattern etc).
The set type can be any of the following:
Set type | # of num. cols | Description |
XY | 2 | An X-Y scatter and/or line plot, plus (optionally) an annotated value |
XYDX | 3 | Same as XY, but with error bars (either one- or two-sided) along X axis |
XYDY | 3 | Same as XYDX, but error bars are along Y axis |
XYDXDX | 4 | Same as XYDX, but left and right error bars are defined separately |
XYDYDY | 4 | Same as XYDXDX, but error bars are along Y axis |
XYDXDY | 4 | Same as XY, but with X and Y error bars (either one- or two-sided) |
XYDXDXDYDY | 6 | Same as XYDXDY, but left/right and upper/lower error bars are defined separately |
BAR | 2 | Same as XY, but vertical bars are used instead of symbols |
BARDY | 3 | Same as BAR, but with error bars (either one- or two-sided) along Y axis |
BARDYDY | 4 | Same as BARDY, but lower and upper error bars are defined separately |
XYHILO | 5 | Hi/Low/Open/Close plot |
XYZ | 3 | Same as XY; makes no sense unless the annotated value is Z |
XYR | 3 | X, Y, Radius. Only allowed in Fixed graphs |
XYSIZE | 3 | Same as XY, but symbol size is variable |
XYCOLOR | 3 | X, Y, color index (of the symbol fill) |
XYCOLPAT | 4 | X, Y, color index, pattern index (currently used for Pie charts only) |
XYVMAP | 4 | Vector map |
XYBOXPLOT | 6 | Box plot (X, median, upper/lower limit, upper/lower whisker) |
Not all set types, however, can be plotted on any graph type. The following table summarizes it:
Set type | XY Graph | XY Chart | Fixed | Polar | Pie |
XY | + | + | + | + | + |
XYDX | + | - | + | - | - |
XYDY | + | + | + | - | - |
XYDXDX | + | - | + | - | - |
XYDYDY | + | + | + | - | - |
XYDXDY | + | - | + | - | - |
XYDXDXDYDY | + | - | + | - | - |
BAR | + | + | + | - | - |
BARDY | - | + | - | - | - |
BARDYDY | - | + | - | - | - |
XYHILO | + | - | - | - | - |
XYZ | + | - | + | + | - |
XYR | - | - | + | - | - |
XYSIZE | + | + | + | + | - |
XYCOLOR | + | + | + | + | + |
XYCOLPAT | - | - | - | - | + |
XYVMAP | + | - | + | - | - |
XYBOXPLOT | + | - | - | - | - |
Regions are sections of a graph defined by the interior or exterior of a polygon, or a half plane defined by a line. Regions are used to restrict data transformations to a geometric area covered by region.
Regions are auxiliary objects which are not displayed in print outputs.
A project file contains all information necessary to restore a plot created by Grace. Each plot is represented on a single page (this may change in future), but may have an unlimited number of graphs.You create a project file of your current graph with File/Save,Save as.
A dataset is a collection of points with X and Y coordinates, up to four optional data values (which, depending on the set presentation type, can be displayed as error bars or like) and one optional character string.
Grace understands several input files formats. The most basic one is ASCII text files containing space and comma separated columns of data. The data fields can be either numeric (Fortran 'd' and 'D' exponent markers are supported) or alphanumeric (with or without quotes). Several calendar date formats are recognized automatically and you can specify your own reference for numeric dates formats. Depending on configuration, Grace can also read NetCDF files (see configuration).
Real Time Input refers to the ability Grace has to be fed in real time by an external program. The Grace process spawned by the driver program is a full featured Grace process: the user can interact using the GUI at the same time the program sends data and commands. The process will adapt itself to the incoming data rate.
Hotlinks are sources containing varying data. Grace can be instructed a file or a pipe is a hotlink in which case it will provide specific commands to refresh the data on a mouse click (a later version will probably allow automatic refresh).
Grace allows the user to choose between several output devices to produce its graphics. The current list of supported devices is:
Grace can also be instructed to launch conversion programs automatically based on file name. As an example you can produce many vector formats using pstoedit, or almost any image format using the netpbm suite (see also the FAQ).
In many cases, when Grace needs to access a file given with a
relative pathname
, it searches for the file along the
following path:
./pathname:./.grace/pathname:~/.grace/pathname:$GRACE_HOME/pathname
Grace can access external functions present in either system or third-party shared libraries or modules specially compiled for use with it. The term dynamic refers to the possibility Grace has to open the library at run time to find the code of the external function, there is no need to recompile Grace itself (the functions already compiled in Grace are "statically linked").
With respect to the user interface, there are three modes of
operation that Grace can be invoked in. The full-featured GUI-based
version is called xmgrace
. A batch-printing version is
called gracebat
. A command-line interface mode is called
grace
. Usually, a single executable is called in all cases,
with two of the three files being (symbolic) links to a "real" one.
Set autoscale type
Turn off all toolbars
Assume data file is block data
Form a set from the current block data set using the current set type from columns given in the argument
Set the hint for dates analysis
Read data from descriptor (anonymous pipe) on startup
Set canvas size fixed to width*height
Use free page layout
No interactive session, just print and quit
Set default hardcopy device
Set options for default hardcopy device
Install private colormap
Assume the answer is yes to all requests - if the operation would overwrite a file, Grace will do so without prompting
Don't use private colormap
In batch mode, do not print
Don't catch signals
Read data from named pipe on startup
Assume data file is in X Y1 Y2 Y3 ... format
Save print output to file
Write results of some data manipulations to results_file
Save all graphs to save_file
Integer seed for random number generator
Source type of next data file
Set allowed time slice for real time inputs to delay ms
Set the type of the next data file
Show the program version
Set the working directory
This message
Set the location of Grace. This will be where help files, auxiliary programs, and examples are located. If you are unable to find the location of this directory, contact your system administrator.
Print command. If the variable is defined but is an empty string, "Print to file" will be selected as default.
The editor used for manual editing of dataset values.
Invocation string of an HTML viewer for on-line browsing of help documents. Must include "%s" to be replaced with an URL string.
These flags control behavior of the FFTW planner (see FFTW tuning for detailed info).
Whenever a new project is started, Grace loads the default template,
templates/Default.xgr
. The file is searched for in the magic
path (see
magic path); once found, the
rest of the path is ignored.
The following Grace-specific X resource settings are supported:
It is also possible to customize menus by assigning key accelerators to any item.
You'll need to derive the item's X resource name from the respective menu label, which is easily done following these rules:
For example, in order to make Grace popup the Non-linear curve fitting by pressing Control+F, you would add the following two lines
XMgrace*transformationsMenu.nonLinearCurveFittingButton.acceleratorText: Ctrl+F
XMgrace*transformationsMenu.nonLinearCurveFittingButton.accelerator: Ctrl<Key>f
to your .Xresources
file (the file which is read when an X
session starts; it could be .Xdefaults
, .Xsession
or
some other file - ask your system administrator when in doubt).
Similarly, it may be desirable to alter default filename patterns of file selection dialogs. The recipe for the dialog's name is like for menu buttons outlined above, with "Button" being replaced with "FSB". E.g., to list all files in the "Open project" dialog ("File/Open..."), set the following resource:
XMgrace*openProjectFSB.pattern: *
This section describes interface controls - basic building blocks, used in many popups.
Whenever the user is expected to provide a filename, either for reading in or writing some data, a file selection dialog is popped up. In addition to the standard entries (the directory and file lists and the filter entry), there is a pulldown menu for quick directory change to predefined locations (the current working directory, user's home directory and the file system root). Also, a "Set as cwd" button is there which allows to set any directory as you navigate through the directory tree as the current working directory (cwd). Once defined, it can be used in any other file selection dialog to switch to that directory quickly.
Various selectors are available in several popups. They all display lists of objects (graphs, sets, ...) and can be used to perform simple operations on these objects (copying, deleting, ...). The operations are available from a popup menu that appears when pressing mouse button 3 on them. Depending on the required functionality, they may allow multiple choices or not.
The following shortcuts are enabled (if the result of an action would contradict the list's selection policy, this would be ignored):
An extension of the list selector. The additional operations that can be performed on frames through the frame selector's popup menu are:
An extension of the list selector. The additional operations that can be performed on graphs through the graph selector's popup menu are:
Double-clicking on a list entry will switch the focus to that graph.
An extension of the list selector. The additional operations that can be performed on sets through the set selector's popup menu are:
Double-clicking on a list entry will open the spreadsheet editor (see Spreadsheet data set editor) on the set data.
Pen chooser lets you select a pen (a color+pattern combination) for drawing a line or filling in an object. When you click on the button, a dialog with color and pattern selectors will appear. When applied, the pen chooser will itself be painted by the pen. A faster way to alter pen's color is to press the right mouse button on it, which will invoke a color-change menu.
The dialog presents an editable matrix of numbers, corresponding to the data set being edited. The set type (and hence, the number of data columns) can be changed using the "Type:" selector. Clicking on a column label pops up a dialog allowing to adjust the column formatting. Clicking on the row labels toggles the respective row state (selected/unselected). The selected rows can be deleted via the dialog's "Edit" menu. Another entry in this menu lets you add a row; the place of the new row is determined by the row containing a cell with the keyboard focus on. As well, just typing in an empty cell will add one or several rows (filling the intermediate rows with zeros).
To resize columns, drag the vertical rules using Shift+Button 2.
When the pointer focus is on the canvas (where the graph is drawn), there are some shortcuts to activate several actions. They are:
A single click inside a graph switches focus to that graph. This is the default policy, but it can be changed from the "Edit/Preferences" popup.
Double clicking on parts of the canvas will invoke certain actions or raise some popups:
The double clicking actions can be enabled/disabled from the "Edit/Preferences" popup.
Along the left-hand side of the canvas (if shown) is the ToolBar. It is armed with several buttons to provide quick and easy access to the more commonly used Grace functions.
Draw
: This will redraw the canvas and sets.
Useful if "Auto Redraw" has been deselected in the "Edit/Preferences"
dialog or after executing commands directly from the "Tools/Console"
dialog. Lens
: A zoom lens. Click on the lens, then select the
area of interest on the graph with the "rubber band". The region
enclosed by the rubber band will fill the entire graph. AS
: AutoScale. Autoscales the graph to contain all
data points of all visible (not hidden) sets. Z/z
: Zoom in/out by 5%. The zoom percentage can be
set in the Edit/Preferences dialog.Arrows
: Scroll active graph by 5% in the arrow's
direction. The scroll percentage can be set in the
Edit/Preferences dialog.AutoT
: AutoTick Axes. This will find the optimum
number of major and minor tick marks for both axes.ZX,ZY
: Zoom along an axis. These buttons work like the
zoom lens above but are restricted to a single axis. AX,AY
: Autoscale one axis only.Exit
: Pretty obvious, eh?The file menu contains all entries related to the input/output features of Grace.
Reset the state of Grace as if it had just started (one empty graph ranging from 0 to 1 along both axes). If some work has been done and not yet saved, a warning popup is displayed to allow canceling the operation.
Open an existing project file. A popup is displayed that allow to browse the file system.
Save the current work in a project file, using the name that was used for the last open or save. If no name has been set (i.e., if the project has been created from scratch) act as save as.
Save the current work in a project file with a new name. A popup allows to browse the file system and set the name, the format to use for saving data points (the default value is "%16.8g"), and a textual description of the project. A warning is displayed if a file with the same name already exists.
Abandon all modifications performed on the project since the last save. A confirmation popup is fired to allow the user canceling the operation.
Set the properties of the printing device. Each device has its own set of specific options (see Device-specific settings). According to the device, the output can be sent either directly to a printer or directed to a file. The global settings available for all devices are the sizing parameters. The size of the graph is fixed. Changing the 'Page' settings changes the size of the canvas underneath the graph. Switching between portrait and landscape rotates the canvas. Make sure the canvas size is large enough to hold your graph. Otherwise you get a 'Printout truncated' warning. If your canvas size cannot easily be changed because, for example, you want to print on letter size paper, you need to adjust the size of your graph ('Viewport' in Plot/Graph Appearance).
Print the project using the current printer settings
Exit from Grace. If some work has been done and not saved, a warning popup will be displayed to allow the user to cancel the operation.
This is the most complex dialog. It allows to tune presentation properties of any plot element.
The left pane of the dialog shows the current project's tree structure. By clicking on a node, a "plugin" dialog corresponding to the quark selected appears in the right pane. A few quarks of the same type can be selected; in this case, changes will be applied to all of them.
The project properties dialog lets you set page dimensions and the background color.
The frame properties dialog governs location of the frame rectangle and legend properties.
The main tab includes the properties you will need more often, in particular, properties related to the graph's coordinate frame. For each axis, you can define the axis range and a scale types: linear, logarithmic, or reciprocal, and you can invert the axis (which normally increases from left to right and from bottom to top).
The "Locator" tab allows you to customize the display of the locator, mainly its type and the format and precision of the display.
The main tab gathers the properties you will need more often (line and symbol properties or legend string for example), and other tabs are used to fine tune some less frequently used options (drop lines, fill properties, annotated values and error bars properties for example).
You should note that, despite the legend string (related to one given set) is entered in the set properties popup, this is not sufficient to display it. Displaying all legends is a frame-level decision, so the toggle is in the main tab of the frame properties plugin dialog.
If you need special characters or special formatting in your legend, you can use Grace escape sequences (the sequence will appear verbatim in the text field but will be rendered on the graph), see typesetting. If you don't remember the mapping between alphabetic characters and the glyph you need in some specific fonts (mainly symbol and zapfdingbats), you can invoke the font tool from the text field by hitting CTRL-e. You can change fonts and select characters from there, they will be copied back in the text field when you press the "Accept" button.
The main tab includes the properties you will need more often (axis label, tick spacing and format for example), and other tabs are used to fine tune some less frequently used options (fonts, sizes, colors, placements, stagger, grid lines, special ticks, ...).
If you need special characters or special formatting in your label, you can use Grace escape sequences (the sequence will appear verbatim in the text field but will be rendered on the graph), see typesetting. If you don't remember the mapping between alphabetic characters and the glyph you need in some specific fonts (mainly symbol and zapfdingbats), you can invoke the font tool from the text field by hitting CTRL-e. You can change fonts and select characters from there, they will be copied back in the text field when you press the "Accept" button.
Not written yet...
Not written yet...
This dialog is incomplete as of yet.
This entry fires up a popup to lay out several graph frames in a regular grid given by M rows and N columns.
The frame selector at the top allows one to select a number of frames the arrangement will operate on. If the number of selected frames isn't equal to M times N, new frames may be created or extra frames killed if needed. These options are controlled by the respective checkboxes below the frame selector.
The order in which the matrix is filled in with the frames can be selected (first horizontally then vertically or vise versa, with either of them inverted).
The rest of the controls of the dialog window deal with the matrix spacing: left/right/top/bottom page offsets (in the viewport coordinates) and relative inter-cell distances, vertical and horizontal. Next to each of the vertical/horizontal spacing spinboxes, a "Pack" checkbox is found. Enabling it effectively sets the respective inter-cell distance to zero.
If you don't want the regular layout this arrangement gives you, you can change it afterwards.
Using this entry, you can autoscale a graph according to the specified sets only. This is useful if you need either to have truly comparable graphs despite every one contains data of different ranges, or if you want to focus your attention on one set only while it is displayed with other data in a complex graph.
The preferences popup allows you to set miscellaneous properties of your Grace session, such as GUI behavior, cursor type, etc.
This popup gathers all operations that are related to the ordering of data points inside a set or between sets. You can sort according to any coordinate (X, Y, DX, ...) in ascending or descending order, reverse the order of the points, join several sets into one, split one set into several others of equal lengths, or drop a range of points from a set.
The transformations sub-menu gives you access to all data-mining features of Grace.
Using evaluate expression allows you to create a set by applying an explicit formula to another set, or to parts of another set if you use regions restrictions.
All the classical mathematical functions are available (cos, sin, but also lgamma, j1, erf, ...). As usual all trigonometric functions use radians by default but you can specify a unit if you prefer to say cos (x rad) or sin (3 * y deg). For the full list of available numerical functions and operators, see Operators and functions.
In the formula, you can use X, Y, Y1, ..., Y4 to denote any coordinate you like from the source set. An implicit loop will be used around your formula so if you say:
x = x - 4966.5
you will shift all points of your set 4966.5 units to the left.
You can use more than one set in the same formula, like this:
y = y - 0.653 * sin (x deg) + s2.y
which means you use both X and Y from the source set but also the Y coordinate of set 2. Beware that the loop is a simple loop over the indices, all the sets you use in such an hybrid expression should therefore have the same number of points and point i of one set should really be related to point i of the other set. If your sets do not follow these requirements, you should first homogenize them using interpolation.
The histograms popup allows you to compute either standard or cumulative histograms from the Y coordinates of your data. Optionally, the histograms can be normalized to 1 (hence producing a PDF (Probability Distribution Function).
The bins can be either a linear mesh defined by its min, max, and length values, or a mesh formed by abscissas of another set (in which case abscissas of the set must form a strictly monotonic array).
This popup is devoted to direct and inverse Fourier transforms. The default is to perform a direct transform on unfiltered data and to produce a set with the index as abscissa and magnitude as ordinate. You can filter the input data window through triangular, Hanning, Welch, Hamming, Blackman and Parzen filters. You can load magnitude, phase or coefficients and use either index, frequency or period as abscissas. You can choose between direct and inverse Fourier transforms. If you specify real input data, X is assumed to be equally spaced and ignored; if you specify complex input data X is taken as the real part and Y as the imaginary part.
If Grace was configured with the FFTW library (see configuration), then the DFT and FFT buttons really perform the same transform (so there is no speed-up in using FFT in this case). If you want Grace can to use FFTW wisdom files, you should set several environment variables to name them.
The running properties popup allows you to compute some values on a sliding window over your data. You choose both the value you need (average, median, minimum, maximum, standard deviation) and the length of the window and perform the operation.
The differences popup is used to compute approximations of the first derivative of a function with finite differences. a period to data of the preceding period (namely y[i] - y[i + period]). Beware that the period is entered in terms of index in the set and not in terms of abscissa!
The integration popup is used to compute the integral of a set and optionally to load it. The numerical value of the integral is shown in the text field after computation. Selecting "cumulative sum" in the choice item will create and load a new set with the integral and compute the end value, selecting "sum only" will only compute the end value.
This popup is used to interpolate a set on an array of alternative X coordinates. This is mainly used before performing some complex operations between two sets with the evaluate expression popup.
The sampling array can be either a linear mesh defined by its min, max, and length values, or a mesh formed by abscissas of another set.
Several interpolation methods can be used: linear, spline or Akima spline.
Note that if the sampling mesh is not entirely within the source set X bounds, evaluation at the points beyond the bounds will be performed using interpolation parameters from the first (or the last) segment of the source set, which can be considered a primitive extrapolation. This behaviour can be disabled by checking the "Strict" option on the popup.
The abscissas of the set being interpolated must form a strictly monotonic array.
The non linear fit popup can be used for functions outside of the simple regression methods scope. With this popup you provide the expression yourself using a0, a1, ..., a9 to denote the fit parameters (as an example you can say y = a0 * cos (a1 * x + a2)). You specify a tolerance, starting values and optional bounds and run several steps before loading the results.
The fit characteristics (number of parameters, formula, ...) can be saved in a file and retrieved as needed using the file menu of the popup.
In the "Advanced" tab, you can additionally apply a restriction to the set(s) to be fitted (thus ignoring points not satisfying the criteria), use one of preset weighting schemes or define your own (notice that "dY" in the preset "1/dY^2" one actually refers to the third column of the data set; use the "Custom" function if this doesn't make sense for your data set), and choose whether to load the fitted values, the residuals or the function itself. Choosing to load fitted values or residuals leads to a set of the same length and abscissas as the initial set. Choosing to load the function is almost similar to load the fitted values except that you choose yourself the boundaries and the number of points. This can be used for example to draw the curve outside of the data sample range or to produce an evenly spaced set from an irregular one.
This popup can be used to compute autocorrelation of one set or cross correlation between two sets. You only select the set (or sets) and specify the maximum lag. A check box allows one to evaluate covariance instead of correlation. The result is normalized so that abs(C(0)) = 1.
The convolution popup is used to ... convolve two sets. You only select the sets and apply.
This popup provides a way to sample a set by selecting only the points that satisfy a boolean expression you specify.
This popup is devoted to reducing huge sets (and then saving both computation time and disk space).
The interpolation method can be applied only to ordered sets: it is based on the assumption that if a real point and an interpolation based on neighboring points are closer than a specified threshold, then the point is redundant and can be eliminated.
The geometric methods (circle, ellipse, rectangle) can be applied to any set, they test each point in turn and keep only those that are not in the neighborhood of previous points.
Given a set of curves in a graph, extract a feature from each curve and use the values of the feature to provide the Y values for a new curve.
Read new sets of data in a graph. A graph selector is used to specify the graph where the data should go (except when reading block data, which are copied to graphs later on).
Reading as "Single set" means that if the source contains only one column of numeric data, one set will be created using the indices (from 1 to the total number of points) as abscissas and read values as ordinates and that if the source contains more than one column of data, the first two numeric columns will be used. Reading as "NXY" means that the first numeric column will provide the abscissas and all remaining columns will provide the ordinates of several sets. Reading as "Block data" means all column will be read and stored and that another popup will allow to select the abscissas and ordinates at will. It should be noted that block data are stored as long as you do not override them by a new read. You can still retrieve data from a block long after having closed all popups, using the set selector.
The set type can be one of the predefined set presentation types (see sets).
The data source can be selected as "Disk" or "Pipe". In the first case the text in the "Selection" field is considered to be a file name (it can be automatically set by the file selector at the top of the popup). In the latter case the text is considered to be a command which is executed and should produce the data on its standard output. On systems that allows is, the command can be a complete sequence of programs glued together with pipes.
If the source contains date fields, they should be automatically detected. Several formats are recognized (see appendix dates in grace). Calendar dates are converted to numerical dates upon reading.
The "Autoscale on read" menu controls whether, upon reading in new sets, which axes of the graph should be autoscaled.
This entry exists only if Grace has been compiled with support for the NetCDF data format (see configuration).
Save data sets in a file. A set selector is used to specify the set to be saved. The format to use for saving data points can be specified (the default value is "%16.8g"). A warning is displayed if a file with the same name already exists.
This toggle item shows or hides the locator below the menu bar.
This toggle item shows or hides the status string below the canvas.
This toggle item shows or hides the tool bar at the left of the canvas.
Zoom out page.
Zoom in page.
Reset page zoom.
Set the rendering properties of the display device (font anti-aliasing and color transformations).
This menu item triggers a redrawing of the canvas.
This menu item causes an update of all GUI controls. Usually, everything is updated automatically, unless one makes modifications by entering commands in the Console tool.
Not written yet...
The console window displays errors and results of some numerical operations, e.g. nonlinear fit (see Non-linear fit). The window is popped up automatically whenever an error occurs or new result messages appear. This can be altered by checking the "Options/Popup only on errors" option.
The dialog also provides an interface to the command driven version of Grace. Here, commands can be typed in the "Command:" text item and executed when <Return> is pressed. The command will be parsed and executed, and the command line is placed in the history list. Items in the history list can be recalled by using the keyboard arrow buttons. Depending on the state of the "Options/Auto redraw" and "Options/Auto update" checkboxes, each command entered will cause an immediate resync of the canvas and/or the GUI, respectively. For a reference on the Grace command interpreter, see Command interpreter.
Using the dataset statistics popup, you can view statistical properties of datasets (min, max, mean, standard deviation). A horizontal scrollbar at the bottom allows to get the two last properties, they are not displayed by default. Also note that if you find some columns are too narrow to show all significant digits, you can drag the vertical rules using Shift+Button 2.
Click on any element of the interface to get context-sensitive help on it. Only partially implemented at the moment.
Browse the Grace user's guide.
Frequently Asked Questions with answers.
The list of changes during the Grace development.
The whole tree of submenus each loading a sample plot.
Open the official Grace home page.
Go to Grace forums, where you can participate in discussions.
Use this to send your suggestions or bug reports.
Grace licensing terms will be displayed (GPL version 2).
A popup with basic info on the software, including some configuration details. More details can be found when running Grace with the "-version" command line flag.
The interpreter parses its input in a line-by-line manner. There may
be several statements per line, separated by semicolon (;
).
The maximal line length is 4 kbytes (hardcoded). The parser is
case-insensitive and ignores lines beginning with the "#
" sign.
Name | Description | Examples |
expr | Any numeric expression | 1.5 + sin(2) |
iexpr | Any expression that evaluates to an integer | 25, 0.1 + 1.9, PI/asin(1) |
nexpr | Non-negative iexpr | 2 - 1 |
indx | Non-negative iexpr | |
qstr | Quoted string | "a string" |
Expression | Description | Types | Example |
X | the first column | - | X |
Y | the second column | - | Y |
Yn | (n + 2)-th column | n = 0 - 4 | Y3 |
Not finished yet...
Variable | Description |
datacolumn | data column of current set |
set.datacolumn | data column of set |
vvar | user-defined array |
Variable | Description |
vvariable[i] | i-th element of a vector variable |
var | user-defined variable |
In numerical expressions, the infix format is used. Arguments of both operators and functions can be either scalars or vector arrays.
Operator | Description |
+ | addition |
- | substraction |
* | multiplication |
/ | division |
% | modulus |
^ | raising to power |
Operator | Description |
AND or && | logical AND |
OR or || | logical OR |
NOT or ! | logical NOT |
Operator | Description |
EQ or == | equal |
NE or != | not equal |
LT or < | less than |
LE or <= | less than or equal |
GT or > | greater than |
GE or >= | greater than or equal |
Function | Description |
abs(x) | absolute value |
acos(x) | arccosine |
acosh(x) | hyperbolic arccosine |
asin(x) | arcsine |
asinh(x) | hyperbolic arcsine |
atan(x) | arctangent |
atan2(y,x) | arc tangent of two variables |
atanh(x) | hyperbolic arctangent |
ceil(x) | greatest integer function |
cos(x) | cosine |
cosh(x) | hyperbolic cosine |
exp(x) | e^x |
fac(n) | factorial function, n! |
floor(x) | least integer function |
irand(n) | random integer less than n |
ln(x) | natural log |
log10(x) | log base 10 |
log2(x) | base 2 logarithm of x |
maxof(x,y) | returns greater of x and y |
mesh(n) | mesh array (0 ... n - 1) |
mesh(x1, x2, n) | mesh array of n equally spaced points between x1 and x2 inclusive |
minof(x,y) | returns lesser of x and y |
mod(x,y) | mod function (also x % y) |
pi | the PI constant |
rand | pseudo random number distributed uniformly on (0.0,1.0) |
rand(n) | array of n random numbers |
rint(x) | round to closest integer |
sin(x) | sine function |
sinh(x) | hyperbolic sine |
sqr(x) | x^2 |
sqrt(x) | x^0.5 |
tan(x) | tangent function |
tanh(x) | hyperbolic tangent |
Function | Description |
chdtr(df, x) | chi-square distribution |
chdtrc(v, x) | complemented Chi-square distribution |
chdtri(df, y) | inverse of complemented Chi-square distribution |
erf(x) | error function |
erfc(x) | complement of error function |
fdtr(df1, df2, x) | F distribution function |
fdtrc(x) | complemented F distribution |
fdtri(x) | inverse of complemented F distribution |
gdtr(a, b, x) | gamma distribution function |
gdtrc(a, b, x) | complemented gamma distribution function |
ndtr(x) | Normal distribution function |
ndtri(x) | inverse of Normal distribution function |
norm(x) | gaussian density function |
pdtr(k, m) | Poisson distribution |
pdtrc(k, m) | complemented Poisson distribution |
pdtri(k, y) | inverse Poisson distribution |
rnorm(xbar,s) | pseudo random number distributed N(xbar,s) |
stdtr(k, t) | Student's t distribution |
stdtri(k, p) | functional inverse of Student's t distribution |
Function | Description |
ai(x), bi(x) | Airy functions (two independent solutions of the differential equation y''(x) = xy ) |
beta(x) | beta function |
chi(x) | hyperbolic cosine integral |
ci(x) | cosine integral |
dawsn(x) | Dawson's integral |
ellie(phi, m) | incomplete elliptic integral of the second kind |
ellik(phi, m) | incomplete elliptic integral of the first kind |
ellpe(m) | complete elliptic integral of the second kind |
ellpk(m) | complete elliptic integral of the first kind |
expn(n, x) | exponential integral |
fresnlc(x) | cosine Fresnel integral |
fresnls(x) | sine Fresnel integral |
gamma(x) | gamma function |
hyp2f1(a, b, c, x) | Gauss hyper-geometric function |
hyperg(a, b, x) | confluent hyper-geometric function |
i0e(x) | modified Bessel function of order zero, exponentially scaled |
i1e(x) | modified Bessel function of order one, exponentially scaled |
igam(a, x) | incomplete gamma integral |
igamc(a, x) | complemented incomplete gamma integral |
igami(a, p) | inverse of complemented incomplete gamma integral |
incbet(a, b, x) | incomplete beta integral |
incbi(a, b, y) | Inverse of incomplete beta integral |
iv(v, x) | modified Bessel function of order v |
jv(v, x) | Bessel function of order v |
k0e(x) | modified Bessel function, third kind, order zero, exponentially scaled |
k1e(x) | modified Bessel function, third kind, order one, exponentially scaled |
kn(n, x) | modified Bessel function, third kind, integer order |
lbeta(x) | natural log of |beta(x)| |
lgamma(x) | log of gamma function |
psi(x) | psi (digamma) function |
rgamma(x) | reciprocal gamma function |
shi(x) | hyperbolic sine integral |
si(x) | sine integral |
spence(x) | dilogarithm |
struve(v, x) | Struve function |
yv(v, x) | Bessel function of order v |
zeta(x, q) | Riemann zeta function of two arguments |
zetac(x) | Riemann zeta function |
For all devices, Grace uses Type1 fonts. Both PFA (ASCII) and PFB (binary) formats can be used.
The file responsible for the font configurations of Grace is
fonts/FontDataBase
. The first line contains a positive integer
specifying the number of fonts declared in that file. All remaining lines
contain declarations of one font each, composed out of three fields:
Here is the default FontDataBase
file:
14
Times-Roman Times-Roman n021003l.pfb
Times-Italic Times-Italic n021023l.pfb
Times-Bold Times-Bold n021004l.pfb
Times-BoldItalic Times-BoldItalic n021024l.pfb
Helvetica Helvetica n019003l.pfb
Helvetica-Oblique Helvetica-Oblique n019023l.pfb
Helvetica-Bold Helvetica-Bold n019004l.pfb
Helvetica-BoldOblique Helvetica-BoldOblique n019024l.pfb
Courier Courier n022003l.pfb
Courier-Oblique Courier-Oblique n022023l.pfb
Courier-Bold Courier-Bold n022004l.pfb
Courier-BoldOblique Courier-BoldOblique n022024l.pfb
Symbol Symbol s050000l.pfb
ZapfDingbats ZapfDingbats d050000l.pfb
For text rastering, three types of files are used.
.pfa
-/.pfb
-files: These contain the character
outline descriptions. The files are assumed to be in the
fonts/type1
directory; these are the filenames
specified in the FontDataBase
configuration file..afm
-files: These contain high-precision font metric
descriptions as well as some extra information, such as kerning
and ligature information for a particular font. It is assumed
that the filename of a font metric file has same basename as the
respective font outline file, but with the .afm
extension; the metric files are expected to be found in the
fonts/type1
directory, too..enc
-files: These contain encoding arrays in a special
but simple form. They are only needed if someone wants to load
a special encoding to re-encode a font. Their place is
fonts/enc
It is possible to use custom fonts with Grace. One mostly needs to use
extra fonts for the purpose of localization. For many European
languages, the standard fonts supplied with Grace should contain all the
characters needed, but encoding may have to be adjusted. This is done by
putting a Default.enc
file with proper encoding scheme into the
fonts/enc
directory. Grace comes with a few encoding files in
the directory; more can be easily found on the Internet. (If the
Default.enc
file doesn't exist, the IsoLatin1 encoding will be
used). Notice that for fonts having an encoding scheme in themselves
(such as the Symbol font, and many nationalized fonts) the default
encoding is ignored.
If you do need to use extra fonts, you should modify the
FontDataBase
file accordingly, obeying its format. However,
if you are going to exchange Grace project files with other people who
do not have the extra fonts configured, an important thing is to define
reasonable fall-back font names.
For example, let us assume I use Hebrew fonts, and the configuration file has lines like these:
...
Courier-Hebrew Courier courh___.pfa
Courier-Hebrew-Oblique Courier-Oblique courho__.pfa
...
My colleague, who lives in Russia, uses Cyrillic fonts with Grace
configured like this:
...
Cronix-Courier Courier croxc.pfb
Cronix-Courier-Oblique Courier-Oblique croxco.pfb
...
The font mapping information (Font name <-> Font fall-back) is
stored in the Grace project files. Provided that all the localized fonts
have English characters in the lower part of the ASCII table unmodified,
I can send my friend files (with no Hebrew characters, of course) and be
sure they render correctly on his computer.
Thus, with properly configured national fonts, you can make localized annotations for plots intended for internal use of your institution, while being able to exchange files with colleagues from abroad. People who ever tried to do this with MS Office applications should appreciate the flexibility :-).
When the FFTW capabilities are compiled in, Grace looks at two environment variables to decide what to do with the FFTW 'wisdom' capabilities. First, a quick summary of what this is. The FFTW package is capable of adaptively determining the most efficient factorization of a set to give the fastest computation. It can store these factorizations as 'wisdom', so that if a transform of a given size is to be repeated, it is does not have to re-adapt. The good news is that this seems to work very well. The bad news is that, the first time a transform of a given size is computed, if it is not a sub-multiple of one already known, it takes a LONG time (seconds to minutes).
The first environment variable is GRACE_FFTW_WISDOM_FILE. If this is set to the name of a file which can be read and written (e.g., $HOME/.grace_fftw_wisdom) then Grace will automatically create this file (if needed) and maintain it. If the file is read-only, it will be read, but not updated with new wisdom. If the symbol GRACE_FFTW_WISDOM_FILE either doesn't exist, or evaluates to an empty string, Grace will drop the use of wisdom, and will use the fftw estimator (FFTW_ESTIMATE flag sent to the planner) to guess a good factorization, instead of adaptively determining it.
The second variable is GRACE_FFTW_RAM_WISDOM. If this variable is defined to be non-zero, and GRACE_FFTW_WISDOM_FILE variable is not defined (or is an empty string), Grace will use wisdom internally, but maintain no persistent cache of it. This will result in very slow execution times the first time a transform is executed after Grace is started, but very fast repeats. I am not sure why anyone would want to use wisdom without writing it to disk, but if you do, you can use this flag to enable it.
Grace can access external functions present in either system or third-party shared libraries or modules specially compiled for use with Grace.
One must make sure, however, that the external function is of one
of supported by Grace types:
Grace type | Description |
f_of_i | a function of 1 int variable |
f_of_d | a function of 1 double variable |
f_of_nn | a function of 2 int parameters |
f_of_nd | a function of 1 int parameter and 1 double variable |
f_of_dd | a function of 2 double variables |
f_of_nnd | a function of 2 int parameters and 1 double variable |
f_of_ppd | a function of 2 double parameters and 1 double variable |
f_of_pppd | a function of 3 double parameters and 1 double variable |
The return values of functions are assumed to be of the
double
type.
Note, that there is no difference from the point of view of function prototype between parameters and variables; the difference is in the way Grace treats them - an attempt to use a vector expression as a parameter argument will result in a parse error.
Let us consider few examples.
Caution: the examples provided below (paths and compiler flags) are valid for Linux/ELF with gcc. On other operating systems, you may need to refer to compiler/linker manuals or ask a guru.
Suppose I want to use function pow(x,y)
from the Un*x math
library (libm). Of course, you can use the "^" operator defined
in the Grace language, but here, for the sake of example, we
want to access the function directly.
The command to make it accessible by Grace is
USE "pow" TYPE f_of_dd FROM "/usr/lib/libm.so"
Try to plot y = pow(x,2) and y = x^2 graphs (using, for example, "create new -> Formula" from any set selector) and compare.
Now, let us try to write a function ourselves. We will define
function my_function
which simply returns its (second)
argument multiplied by integer parameter transferred as the
first argument.
In a text editor, type in the following C code and save it as "my_func.c":
double my_function (int n, double x)
{
double retval;
retval = (double) n * x;
return (retval);
}
OK, now compile it:
$gcc -c -fPIC my_func.c
$gcc -shared my_func.o -o /tmp/my_func.so
(You may strip it to save some disk space):
$strip /tmp/my_func.so
That's all! Ready to make it visible to Grace as "myf" - we are too lazy to type the very long string "my_function" many times.
USE "my_function" TYPE f_of_nd FROM "/tmp/my_func.so" ALIAS "myf"
A more serious example. There is a special third-party library available on your system which includes a very important for you yet very difficult-to-program from the scratch function that you want to use with Grace. But, the function prototype is NOT one of any predefined types. The solution is to write a simple function wrapper. Here is how:
Suppose, the name of the library is "special_lib" and the
function you are interested in is called "special_func" and
according to the library manual, should be accessed as void
special_func(double *input, double *output, int parameter)
.
The wrapper would look like this:
double my_wrapper(int n, double x)
{
extern void special_func(double *x, double *y, int n);
double retval;
(void) special_func(&x, &retval, n);
return (retval);
}
Compile it:
$gcc -c -fPIC my_wrap.c
$gcc -shared my_wrap.o -o /tmp/my_wrap.so -lspecial_lib -lblas
$strip /tmp/my_wrap.so
Note that I added -lblas
assuming that the special_lib
library uses some functions from the BLAS. Generally, you have
to add all libraries which your module depends on (and
all libraries those libraries rely upon etc.), as if you wanted
to compile a plain executable.
Fine, make Grace aware of the new function
USE "my_wrapper" TYPE f_of_nd FROM "/tmp/my_wrap.so" ALIAS "special_func"
so we can use it with its original name.
An example of using Fortran modules.
Here we will try to achieve the same functionality as in Example 2, but with the help of F77.
DOUBLE PRECISION FUNCTION MYFUNC (N, X)
IMPLICIT NONE
INTEGER N
DOUBLE PRECISION X
C
MYFUNC = N * X
C
RETURN
END
As opposite to C, there is no way to call such a function from Grace directly - the problem is that in Fortran all arguments to a function (or subroutine) are passed by reference. So, we need a wrapper:
double myfunc_wrapper(int n, double x)
{
extern double myfunc_(int *, double *);
double retval;
retval = myfunc_(&n, &x);
return (retval);
}
Note that most of f77 compilers by default add underscore to
the function names and convert all names to the lower case,
hence I refer to the Fortran function MYFUNC
from my C
wrapper as myfunc_
, but in your case it can be different!
Let us compile the whole stuff:
$g77 -c -fPIC myfunc.f
$gcc -c -fPIC myfunc_wrap.c
$gcc -shared myfunc.o myfunc_wrap.o -o /tmp/myfunc.so -lf2c -lm
$strip /tmp/myfunc.so
And finally, inform Grace about this new function:
USE "myfunc_wrapper" TYPE f_of_nd FROM "/tmp/myfunc.so" ALIAS "myfunc"
In general the method outlined in the examples above can be used on OS/2, too. However you have to create a DLL (Dynamic Link Library) which is a bit more tricky on OS/2 than on most Un*x systems. Since Grace was ported by using EMX we also use it to create the examples; however other development environments should work as well (ensure to use the _System calling convention!). We refer to Example 2 only. Example 1 might demonstrate that DLLs can have their entry points (i.e. exported functions) callable via ordinals only, so you might not know how to access a specific function without some research. First compile the source from Example 2 to "my_func.obj"
gcc -Zomf -Zmt -c my_func.c -o my_func.obj
Then you need to create a linker definition file "my_func.def" which contains some basic info about the DLL and declares the exported functions.
LIBRARY my_func INITINSTANCE TERMINSTANCE
CODE LOADONCALL
DATA LOADONCALL MULTIPLE NONSHARED
DESCRIPTION 'This is a test DLL: my_func.dll'
EXPORTS
my_function
(don't forget about the 8 characters limit on the DLL name!). Finally link the DLL:
gcc my_func.obj my_func.def -o my_func.dll -Zdll -Zno-rte -Zmt -Zomf
(check out the EMX documentation about the compiler/linker flags used here!) To use this new library function within Grace you may either put the DLL in the LIBPATH and use the short form:
USE "my_function" TYPE f_of_nd FROM "my_func" ALIAS "myf"
or put it in an arbitrary path which you need to specify explicitly then:
USE "my_function" TYPE f_of_nd FROM "e:/foo/my_func.dll" ALIAS "myf"
(as for most system-APIs you may use the Un*x-like forward slashs within the path!)
Grace permits quite complex typesetting on a per string basis. Any string displayed (titles, legends, tick marks,...) may contain special control codes to display subscripts, change fonts within the string etc.
Control code | Description |
\f{x} | switch to font named "x" |
\f{n} | switch to font number n |
\f{} | return to original font |
\R{x} | switch to color named "x" |
\R{n} | switch to color number n |
\R{} | return to original color |
\#{x} | treat "x" (must be of even length) as list of hexadecimal char codes |
\t{xx xy yx yy} | apply transformation matrix |
\t{} | reset transformation matrix |
\z{x} | zoom x times |
\z{} | return to original zoom |
\r{x} | rotate by x degrees |
\l{x} | slant by factor x |
\v{x} | shift vertically by x |
\v{} | return to unshifted baseline |
\V{x} | shift baseline by x |
\V{} | reset baseline |
\h{x} | horizontal shift by x |
\n | new line |
\u | begin underline |
\U | stop underline |
\o | begin overline |
\O | stop overline |
\Fk | enable kerning |
\FK | disable kerning |
\Fl | enable ligatures |
\FL | disable ligatures |
\m{n} | mark current position as n |
\M{n} | return to saved position n |
\dl | LtoR substring direction |
\dr | RtoL substring direction |
\dL | LtoR text advancing |
\dR | RtoL text advancing |
\${x} | macro x |
\x | switch to Symbol font (same as \f{Symbol}) |
\+ | increase size (same as \z{1.19} ; 1.19 = sqrt(sqrt(2))) |
\- | decrease size (same as \z{0.84} ; 0.84 = 1/sqrt(sqrt(2))) |
\s | begin subscripting (same as \v{-0.4}\z{0.71}) |
\S | begin superscripting (same as \v{0.6}\z{0.71}) |
\T{xx xy yx yy} | same as \t{}\t{xx xy yx yy} |
\Z{x} | absolute zoom x times (same as \z{}\z{x}) |
\q | make font oblique (same as \l{0.25}) |
\Q | undo oblique (same as \l{-0.25}) |
\N | return to normal style (same as \v{}\t{}) |
\\ | print \ |
\n | switch to font number n (0-9) (deprecated) |
\c | begin using upper 128 characters of set (deprecated) |
\C | stop using upper 128 characters of set (deprecated) |
Example:
F\sX\N(\xe\f{}) = sin(\xe\f{})\#{b7}e\S-X\N\#{b7}cos(\xe\f{})
prints roughly
-x
F (e) = sin(e)·e ·cos(e)
x
using string's initial font and e prints as epsilon from the Symbol font.
NOTE:
Characters from the upper half of the char table can be entered directly
from the keyboard, using appropriate xmodmap(1)
settings, or
with the help of the font tool ("Tools/Font tool").
Grace can output plots using several device backends. The list of available devices can be seen (among other stuff) by specifying the "-version" command line switch.
Some of the output devices accept several configuration options. A few options can be passed in one command, separated by commas. NIY!
Command | Description |
level1 | use only PS Level 1 subset of commands |
level2 | use also PS Level 2 commands if needed |
colorspace:grayscale | set grayscale colorspace |
colorspace:rgb | set RGB colorspace |
colorspace:cmyk | set CMYK colorspace (PS Level2 only) |
docdata:7bit | the document data is 7bit clean |
docdata:8bit | the document data is 8bit clean |
docdata:binary | the document data may be binary |
embedfonts:none | don't embed fonts |
embedfonts:but13 | embed all but the 13 standard fonts |
embedfonts:but35 | embed all but the 35 standard fonts |
embedfonts:all | embed all fonts |
xoffset:x | set page offset in X direction x pp |
yoffset:y | set page offset in Y direction y pp |
mediafeed:auto | default input tray |
mediafeed:match | select input with media matching page dimensions |
mediafeed:manual | manual media feed |
hwresolution:on | set hardware resolution |
hwresolution:off | do not set hardware resolution |
Command | Description |
level1 | use only PS Level 1 subset of commands |
level2 | use also PS Level 2 commands if needed |
colorspace:grayscale | set grayscale colorspace |
colorspace:rgb | set RGB colorspace |
colorspace:cmyk | set CMYK colorspace (PS Level2 only) |
docdata:7bit | the document data is 7bit clean |
docdata:8bit | the document data is 8bit clean |
docdata:binary | the document data may be binary |
embedfonts:none | don't embed fonts |
embedfonts:but13 | embed all but the 13 standard fonts |
embedfonts:but35 | embed all but the 35 standard fonts |
embedfonts:all | embed all fonts |
Command | Description |
compatibility:PDF-1.3 | set compatibility mode to PDF-1.3 (Acrobat4) |
compatibility:PDF-1.4 | set compatibility mode to PDF-1.4 (Acrobat5) |
compatibility:PDF-1.5 | set compatibility mode to PDF-1.5 (Acrobat6) |
compression:value | set compression level (0 - 9) |
fpprecision:value | set floating point precision (4 - 6) |
Command | Description |
format:pbm | output in PBM format |
format:pgm | output in PGM format |
format:ppm | output in PPM format |
rawbits:on | "rawbits" (binary) output |
rawbits:off | ASCII output |
Command | Description |
grayscale | set grayscale output |
color | set color output |
optimize:on/off | enable/disable optimization |
quality:value | set compression quality (0 - 100) |
smoothing:value | set smoothing (0 - 100) |
baseline:on/off | do/don't force baseline output |
progressive:on/off | do/don't output in progressive format |
dct:ifast | use fast integer DCT method |
dct:islow | use slow integer DCT method |
dct:float | use floating-point DCT method |
Command | Description |
interlaced:on | make interlaced image |
interlaced:off | don't make interlaced image |
transparent:on | produce transparent image |
transparent:off | don't produce transparent image |
compression:value | set compression level (0 - 9) |
We use two calendars in Grace: the one that was established in 532 by Denys and lasted until 1582, and the one that was created by Luigi Lilio (Alyosius Lilius) and Christoph Klau (Christophorus Clavius) for pope Gregorius XIII. Both use the same months (they were introduced under emperor Augustus, a few years after Julian calendar introduction, both Julius and Augustus were honored by a month being named after each one).
The leap years occurred regularly in Denys's calendar: once every four years, there is no year 0 in this calendar (the leap year -1 was just before year 1). This calendar was not compliant with earth motion and the dates were slowly shifting with regard to astronomical events.
This was corrected in 1582 by introducing Gregorian calendar. First a ten days shift was introduced to reset correct dates (Thursday October the 4th was followed by Friday October the 15th). The rules for leap years were also changed: three leap years are removed every four centuries. These years are those that are multiple of 100 but not multiple of 400: 1700, 1800, and 1900 were not leap years, but 1600 and 2000 were (will be) leap years.
We still use Gregorian calendar today, but we now have several time scales for increased accuracy. The International Atomic Time (TAI) is a linear scale: the best scale to use for scientific reference. The Coordinated Universal Time (UTC, often confused with Greenwich Mean Time) is a legal time that is almost synchronized with earth motion. However, since the earth is slightly slowing down, leap seconds are introduced from time to time in UTC (about one second every 18 months). UTC is not a continuous scale ! When a leap second is introduced by International Earth Rotation Service, this is published in advance and the legal time sequence is as follows: 23:59:59 followed one second later by 23:59:60 followed one second later by 00:00:00. At the time of this writing (1999-01-05) the difference between TAI and UTC was 32 seconds, and the last leap second was introduced in 1998-12-31.
These calendars allow to represent any date from the mist of the past to the fog of the future, but they are not convenient for computation. Another time scale is possible: counting only the days from a reference. Such a time scale was introduced by Joseph-Juste Scaliger (Josephus Justus Scaliger) in 1583. He decided to use "-4713-01-01T12:00:00" as a reference date because it was at the same time a Monday, first of January of a leap year, there was an exact number of 19 years Meton cycle between this date and year 1 (for Easter computation), and it was at the beginning of a 15 years Roman indiction cycle. The day number counted from this reference is traditionally called Julian day, but it has really nothing to do with the Julian calendar.
Grace stores dates internally as reals numbers counted from a reference date. The default reference date is the one chosen by Scaliger, it is a classical reference for astronomical events. It can modified for a single session using the Edit->Preferences popup of the GUI. If you often work with a specific reference date you can set it for every sessions with a REFERENCE DATE command in your configuration file (see Default template).
The following date formats are supported (hour, minutes and seconds are always optional):
One should be aware that Grace does not allow to put a space in one data column as spaces are used to separate fields. You should always use another separator (:/.- or better T) between date and time in data files. The GUI, the batch language and the command line flags do not have this limitation, you can use spaces there without any problem. The T separator comes from the ISO8601 standard. Grace support its use also in european and us formats.
You can also provide a hint about the format ("ISO8601",
"european", "us") using the -datehint command line flag or the
ref name="Edit->Preferences" id="preferences"> popup of the GUI.
The formats are tried in the following order: first the hint
given by the user, then iso, european and us (there is no
ambiguity between calendar formats and numerical formats and
therefore no order is specified for them). The separators
between various fields can be any characters in the set: " :/.-T"
(one or more spaces act as one separator, other characters can
not be repeated, the T separator is allowed only between date and time,
mainly for iso8601), so the string "1999-12 31:23/59" is allowed
(but not recommended). The '-' character is used both as a
separator (it is traditionally used in iso8601 format) and as
the unary minus (for dates in the far past or for numerical
dates). By default years are left untouched, so 99 is a date far
away in the past. This behavior can be changed with the
Edit->preferences popup, or with the
DATE WRAP on
and DATE WRAP YEAR year
commands. Suppose for example that the wrap year is chosen as
1950, if the year is between 0 and 99 and is written with two or
less digits, it is mapped to the present era as follows:
range [00 ; 49] is mapped to [2000 ; 2049]
range [50 ; 99] is mapped to [1950 ; 1999]
with a wrap year set to 1970, the mapping would have been:
range [00 ; 69] is mapped to [2000 ; 2069]
range [70 ; 99] is mapped to [1970 ; 1999]
this is reasonably Y2K compliant and is consistent with current use. Specifying year 1 is still possible using more than two digits as follows: "0001-03-04" is unambiguously March the 4th, year 1. The inverse transform is applied for dates written by Grace, for example as tick labels. Using two digits only for years is not recommended, we introduce a wrap year + 100 bug here so this feature should be removed at some point in the future ...
The date scanner can be used either for Denys's and Gregorian calendars. Inexistent dates are detected, they include year 0, dates between 1582-10-05 and 1582-10-14, February 29th of non leap years, months below 1 or above 12, ... the scanner does not take into account leap seconds: you can think it works only in International Atomic Time (TAI) and not in Coordinated Unified Time (UTC). If you find yourself in a situation were you need UTC, a very precise scale, and should take into account leap seconds ... you should convert your data yourself (for example using International Atomic Time). But if you bother with that you probably already know what to do.
This is a very brief guide describing problems and workarounds for reading in project files saved with Xmgr. You should read the docs or just play with Grace to test new features and controls.