Date: 2015-10-02T22:12:43+00:00

Actual source code: amd.c
petsc-3.6.2 2015-10-02
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      2: #include <petscmat.h>
      3: #include <petsc/private/matorderimpl.h>
      4: #include <amd.h>

      6: #if defined(PETSC_USE_64BIT_INDICES)
      7: #  define amd_AMD_defaults amd_l_defaults
      8: /* the type casts are needed because PetscInt is long long while SuiteSparse_long is long and compilers warn even when they are identical */
      9: #  define amd_AMD_order(a,b,c,d,e,f)    amd_l_order((SuiteSparse_long)a,(SuiteSparse_long*)b,(SuiteSparse_long*)c,(SuiteSparse_long*)d,e,f)
     10: #else
     11: #  define amd_AMD_defaults amd_defaults
     12: #  define amd_AMD_order    amd_order
     13: #endif

     15: /*
     16:     MatGetOrdering_AMD - Find the Approximate Minimum Degree ordering

     18:     This provides an interface to Tim Davis' AMD package (used by UMFPACK, CHOLMOD, MATLAB, etc).
     19: */
     22: PETSC_EXTERN PetscErrorCode MatGetOrdering_AMD(Mat mat,MatOrderingType type,IS *row,IS *col)
     23: {
     25:   PetscInt       nrow,*perm;
     26:   const PetscInt *ia,*ja;
     27:   int            status;
     28:   PetscReal      val;
     29:   double         Control[AMD_CONTROL],Info[AMD_INFO];
     30:   PetscBool      tval,done;

     33:   /*
     34:      AMD does not require that the matrix be symmetric (it does so internally,
     35:      at least in so far as computing orderings for A+A^T.
     36:   */
     37:   MatGetRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,&nrow,&ia,&ja,&done);
     38:   if (!done) SETERRQ1(PETSC_COMM_SELF,PETSC_ERR_SUP,"Cannot get rows for matrix type %s",((PetscObject)mat)->type_name);

     40:   amd_AMD_defaults(Control);
     41:   PetscOptionsBegin(PetscObjectComm((PetscObject)mat),((PetscObject)mat)->prefix,"AMD Options","Mat");
     42:   /*
     43:     We have to use temporary values here because AMD always uses double, even though PetscReal may be single
     44:   */
     45:   val  = (PetscReal)Control[AMD_DENSE];
     46:   PetscOptionsReal("-mat_ordering_amd_dense","threshold for \"dense\" rows/columns","None",val,&val,NULL);
     47:   Control[AMD_DENSE] = (double)val;

     49:   tval = (PetscBool)Control[AMD_AGGRESSIVE];
     50:   PetscOptionsBool("-mat_ordering_amd_aggressive","use aggressive absorption","None",tval,&tval,NULL);
     51:   Control[AMD_AGGRESSIVE] = (double)tval;

     53:   PetscOptionsEnd();

     55:   PetscMalloc1(nrow,&perm);
     56:   status = amd_AMD_order(nrow,ia,ja,perm,Control,Info);
     57:   switch (status) {
     58:   case AMD_OK: break;
     59:   case AMD_OK_BUT_JUMBLED:
     60:     /* The result is fine, but PETSc matrices are supposed to satisfy stricter preconditions, so PETSc considers a
     61:     * matrix that triggers this error condition to be invalid.
     62:     */
     63:     SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_PLIB,"According to AMD, the matrix has unsorted and/or duplicate row indices");
     64:   case AMD_INVALID:
     65:     amd_info(Info);
     66:     SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_PLIB,"According to AMD, the matrix is invalid");
     67:   case AMD_OUT_OF_MEMORY:
     68:     SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_MEM,"AMD could not compute ordering");
     69:   default:
     70:     SETERRQ(PetscObjectComm((PetscObject)mat),PETSC_ERR_LIB,"Unexpected return value");
     71:   }
     72:   MatRestoreRowIJ(mat,0,PETSC_FALSE,PETSC_TRUE,NULL,&ia,&ja,&done);

     74:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_COPY_VALUES,row);
     75:   ISCreateGeneral(PETSC_COMM_SELF,nrow,perm,PETSC_OWN_POINTER,col);
     76:   return(0);
     77: }