Actual source code: dsm.c
petsc-3.10.5 2019-03-28
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      1: /* dsm.f -- translated by f2c (version of 25 March 1992  12:58:56). */

      3:  #include <../src/mat/color/impls/minpack/color.h>

      5: static PetscInt c_n1 = -1;

      7: PetscErrorCode MINPACKdsm(PetscInt *m,PetscInt *n,PetscInt *npairs,PetscInt *indrow,PetscInt *indcol,PetscInt *ngrp,PetscInt *maxgrp,
      8:                           PetscInt *mingrp,PetscInt *info,PetscInt *ipntr,PetscInt *jpntr,PetscInt *iwa,PetscInt *liwa)
      9: {
     10:   /* System generated locals */
     11:   PetscInt i__1,i__2,i__3;

     13:   /* Local variables */
     14:   PetscInt i,j,maxclq,numgrp;

     16: /*     Given the sparsity pattern of an m by n matrix A, this */
     17: /*     subroutine determines a partition of the columns of A */
     18: /*     consistent with the direct determination of A. */
     19: /*     The sparsity pattern of the matrix A is specified by */
     20: /*     the arrays indrow and indcol. On input the indices */
     21: /*     for the non-zero elements of A are */
     22: /*           indrow(k),indcol(k), k = 1,2,...,npairs. */
     23: /*     The (indrow,indcol) pairs may be specified in any order. */
     24: /*     Duplicate input pairs are permitted, but the subroutine */
     25: /*     eliminates them. */
     26: /*     The subroutine partitions the columns of A into groups */
     27: /*     such that columns in the same group do not have a */
     28: /*     non-zero in the same row position. A partition of the */
     29: /*     columns of A with this property is consistent with the */
     30: /*     direct determination of A. */
     31: /*     The subroutine statement is */
     32: /*       subroutine dsm(m,n,npairs,indrow,indcol,ngrp,maxgrp,mingrp, */
     33: /*                      info,ipntr,jpntr,iwa,liwa) */
     34: /*     where */
     35: /*       m is a positive integer input variable set to the number */
     36: /*         of rows of A. */
     37: /*       n is a positive integer input variable set to the number */
     38: /*         of columns of A. */
     39: /*       npairs is a positive integer input variable set to the */
     40: /*         number of (indrow,indcol) pairs used to describe the */
     41: /*         sparsity pattern of A. */
     42: /*       indrow is an integer array of length npairs. On input indrow */
     43: /*         must contain the row indices of the non-zero elements of A. */
     44: /*         On output indrow is permuted so that the corresponding */
     45: /*         column indices are in non-decreasing order. The column */
     46: /*         indices can be recovered from the array jpntr. */
     47: /*       indcol is an integer array of length npairs. On input indcol */
     48: /*         must contain the column indices of the non-zero elements of */
     49: /*         A. On output indcol is permuted so that the corresponding */
     50: /*         row indices are in non-decreasing order. The row indices */
     51: /*         can be recovered from the array ipntr. */
     52: /*       ngrp is an integer output array of length n which specifies */
     53: /*         the partition of the columns of A. Column jcol belongs */
     54: /*         to group ngrp(jcol). */
     55: /*       maxgrp is an integer output variable which specifies the */
     56: /*         number of groups in the partition of the columns of A. */
     57: /*       mingrp is an integer output variable which specifies a lower */
     58: /*         bound for the number of groups in any consistent partition */
     59: /*         of the columns of A. */
     60: /*       info is an integer output variable set as follows. For */
     61: /*         normal termination info = 1. If m, n, or npairs is not */
     62: /*         positive or liwa is less than max(m,6*n), then info = 0. */
     63: /*         If the k-th element of indrow is not an integer between */
     64: /*         1 and m or the k-th element of indcol is not an integer */
     65: /*         between 1 and n, then info = -k. */
     66: /*       ipntr is an integer output array of length m + 1 which */
     67: /*         specifies the locations of the column indices in indcol. */
     68: /*         The column indices for row i are */
     69: /*               indcol(k), k = ipntr(i),...,ipntr(i+1)-1. */
     70: /*         Note that ipntr(m+1)-1 is then the number of non-zero */
     71: /*         elements of the matrix A. */
     72: /*       jpntr is an integer output array of length n + 1 which */
     73: /*         specifies the locations of the row indices in indrow. */
     74: /*         The row indices for column j are */
     75: /*               indrow(k), k = jpntr(j),...,jpntr(j+1)-1. */
     76: /*         Note that jpntr(n+1)-1 is then the number of non-zero */
     77: /*         elements of the matrix A. */
     78: /*       iwa is an integer work array of length liwa. */
     79: /*       liwa is a positive integer input variable not less than */
     80: /*         max(m,6*n). */
     81: /*     Subprograms called */
     82: /*       MINPACK-supplied ... degr,ido,numsrt,seq,setr,slo,srtdat */
     83: /*       FORTRAN-supplied ... max */
     84: /*     Argonne National Laboratory. MINPACK Project. December 1984. */
     85: /*     Thomas F. Coleman, Burton S. Garbow, Jorge J. More' */

     88:   /* Parameter adjustments */
     89:   --iwa;
     90:   --jpntr;
     91:   --ipntr;
     92:   --ngrp;
     93:   --indcol;
     94:   --indrow;

     96:   *info = 0;

     98: /*     Determine a lower bound for the number of groups. */

    100:   *mingrp = 0;
    101:   i__1    = *m;
    102:   for (i = 1; i <= i__1; ++i) {
    103:     /* Computing MAX */
    104:     i__2    = *mingrp;
    105:     i__3    = ipntr[i + 1] - ipntr[i];
    106:     *mingrp = PetscMax(i__2,i__3);
    107:   }

    109: /*     Determine the degree sequence for the intersection */
    110: /*     graph of the columns of A. */

    112:   MINPACKdegr(n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[*n * 5 + 1],&iwa[*n + 1]);

    114: /*     Color the intersection graph of the columns of A */
    115: /*     with the smallest-last (SL) ordering. */

    117:   MINPACKslo(n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[*n * 5 + 1],&iwa[(*n << 2) + 1],&maxclq,&iwa[1],&iwa[*n + 1],&iwa[(*n << 1)+ 1],&iwa[*n * 3 + 1]);
    118:   MINPACKseq(n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[(*n << 2) + 1],&ngrp[1],maxgrp,&iwa[*n + 1]);
    119:   *mingrp = PetscMax(*mingrp,maxclq);

    121: /*     Exit if the smallest-last ordering is optimal. */

    123:   if (*maxgrp == *mingrp) return(0);

    125: /*     Color the intersection graph of the columns of A */
    126: /*     with the incidence-degree (ID) ordering. */

    128:   MINPACKido(m,n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[*n * 5 + 1],&iwa[(*n << 2) + 1],&maxclq,&iwa[1],&iwa[*n + 1],&iwa[(*n << 1) + 1],&iwa[*n * 3 + 1]);
    129:   MINPACKseq(n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[(*n << 2) + 1],&iwa[1],&numgrp,&iwa[*n + 1]);
    130:   *mingrp = PetscMax(*mingrp,maxclq);

    132: /*     Retain the better of the two orderings so far. */

    134:   if (numgrp < *maxgrp) {
    135:     *maxgrp = numgrp;
    136:     i__1    = *n;
    137:     for (j = 1; j <= i__1; ++j) ngrp[j] = iwa[j];

    139: /*        Exit if the incidence-degree ordering is optimal. */

    141:     if (*maxgrp == *mingrp) return(0);
    142:   }

    144: /*     Color the intersection graph of the columns of A */
    145: /*     with the largest-first (LF) ordering. */

    147:   i__1 = *n - 1;
    148:   MINPACKnumsrt(n,&i__1,&iwa[*n * 5 + 1],&c_n1,&iwa[(*n << 2) + 1],&iwa[(*n << 1) + 1],&iwa[*n + 1]);
    149:   MINPACKseq(n,&indrow[1],&jpntr[1],&indcol[1],&ipntr[1],&iwa[(*n << 2) + 1],&iwa[1],&numgrp,&iwa[*n + 1]);

    151: /*     Retain the best of the three orderings and exit. */

    153:   if (numgrp < *maxgrp) {
    154:     *maxgrp = numgrp;
    155:     i__1    = *n;
    156:     for (j = 1; j <= i__1; ++j) ngrp[j] = iwa[j];
    157:   }
    158:   return(0);
    159: }