Actual source code: amd.c


  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: */
 20: PETSC_INTERN PetscErrorCode MatGetOrdering_AMD(Mat mat, MatOrderingType type, IS *row, IS *col)
 21: {
 22:   PetscInt        nrow, *perm;
 23:   const PetscInt *ia, *ja;
 24:   int             status;
 25:   PetscReal       val;
 26:   double          Control[AMD_CONTROL], Info[AMD_INFO];
 27:   PetscBool       tval, done;

 29:   PetscFunctionBegin;
 30:   /*
 31:      AMD does not require that the matrix be symmetric (it does so internally,
 32:      at least in so far as computing orderings for A+A^T.
 33:   */
 34:   PetscCall(MatGetRowIJ(mat, 0, PETSC_FALSE, PETSC_TRUE, &nrow, &ia, &ja, &done));
 35:   PetscCheck(done, PETSC_COMM_SELF, PETSC_ERR_SUP, "Cannot get rows for matrix type %s", ((PetscObject)mat)->type_name);

 37:   amd_AMD_defaults(Control);
 38:   PetscOptionsBegin(PetscObjectComm((PetscObject)mat), ((PetscObject)mat)->prefix, "AMD Options", "Mat");
 39:   /*
 40:     We have to use temporary values here because AMD always uses double, even though PetscReal may be single
 41:   */
 42:   val = (PetscReal)Control[AMD_DENSE];
 43:   PetscCall(PetscOptionsReal("-mat_ordering_amd_dense", "threshold for \"dense\" rows/columns", "None", val, &val, NULL));
 44:   Control[AMD_DENSE] = (double)val;

 46:   tval = (PetscBool)Control[AMD_AGGRESSIVE];
 47:   PetscCall(PetscOptionsBool("-mat_ordering_amd_aggressive", "use aggressive absorption", "None", tval, &tval, NULL));
 48:   Control[AMD_AGGRESSIVE] = (double)tval;

 50:   PetscOptionsEnd();

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

 72:   PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_COPY_VALUES, row));
 73:   PetscCall(ISCreateGeneral(PETSC_COMM_SELF, nrow, perm, PETSC_OWN_POINTER, col));
 74:   PetscFunctionReturn(PETSC_SUCCESS);
 75: }