petsc-3.10.5 2019-03-28
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# PetscOptionsScalar

Gets the scalar value for a particular option in the database.

### Synopsis

    #include "petscsys.h"
    PetscErrorCode  PetscOptionsScalar_Private(PetscOptionItems *PetscOptionsObject,const char opt[],const char text[],const char man[],PetscScalar currentvalue,PetscScalar *value,PetscBool  *set)

Logically Collective on the communicator passed in PetscOptionsBegin()

### Input Parameters

| opt | - option name
| text | - short string that describes the option
| man | - manual page with additional information on option
| currentvalue | - the current value; caller is responsible for setting this value correctly. Normally this is done with either

                    PetscOptionsScalar(..., obj->value,&object->value,...) or

                    value = defaultvalue

                    PetscOptionsScalar(..., value,&value,&flg);

                    if (flg) {

### Output Parameter

| value | - the value to return
| flg | - PETSC_TRUE if found, else PETSC_FALSE

### Notes

If the user does not supply the option at all value is NOT changed. Thus you should ALWAYS initialize value if you access it without first checking if the set flag is true.

The default/currentvalue passed into this routine does not get transferred to the output value variable automatically.

### Notes

Must be between a PetscOptionsBegin() and a PetscOptionsEnd()

### See Also

PetscOptionsGetReal(), PetscOptionsHasName(), PetscOptionsGetString(), PetscOptionsGetInt(NULL,),
PetscOptionsGetIntArray(), PetscOptionsGetRealArray(), PetscOptionsBool() PetscOptionsInt(), PetscOptionsString(), PetscOptionsReal(), PetscOptionsBool(), PetscOptionsName(), PetscOptionsBegin(), PetscOptionsEnd(), PetscOptionsHead(), PetscOptionsStringArray(),PetscOptionsRealArray(), PetscOptionsScalar(), PetscOptionsBoolGroupBegin(), PetscOptionsBoolGroup(), PetscOptionsBoolGroupEnd(), PetscOptionsFList(), PetscOptionsEList()

### Level

beginner

### Location

src/sys/objects/aoptions.c

### Examples

src/ksp/ksp/examples/tutorials/ex32.c.html
src/ts/examples/tutorials/ex35.cxx.html
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Index of all manual pages