Date: 2026-07-30T21:14:15+00:00

Actual source code: math2opusutils.cu

      1: #include <petsc/private/matimpl.h>
      2: #include <petsc/private/vecimpl.h>
      3: #include <petscsf.h>
      4: #if defined(PETSC_HAVE_CUDA)
      5:   #include <thrust/for_each.h>
      6:   #include <thrust/device_vector.h>
      7:   #include <thrust/execution_policy.h>
      8: #endif

     10: PETSC_INTERN PetscErrorCode MatDenseGetH2OpusStridedSF(Mat A, PetscSF h2sf, PetscSF *osf)
     11: {
     12:   PetscSF asf;

     14:   PetscFunctionBegin;
     17:   PetscAssertPointer(osf, 3);
     18:   PetscCall(PetscObjectQuery((PetscObject)A, "_math2opus_stridedsf", (PetscObject *)&asf));
     19:   if (!asf) {
     20:     PetscInt lda;

     22:     PetscCall(MatDenseGetLDA(A, &lda));
     23:     PetscCall(PetscSFCreateStridedSF(h2sf, A->cmap->N, lda, PETSC_DECIDE, &asf));
     24:     PetscCall(PetscObjectCompose((PetscObject)A, "_math2opus_stridedsf", (PetscObject)asf));
     25:     PetscCall(PetscObjectDereference((PetscObject)asf));
     26:   }
     27:   *osf = asf;
     28:   PetscFunctionReturn(PETSC_SUCCESS);
     29: }

     31: #if defined(PETSC_HAVE_CUDA)
     32: struct StandardBasis_Functor {
     33:   PetscScalar *v;
     34:   PetscInt     j;

     36:   StandardBasis_Functor(PetscScalar *_v, PetscInt _j) : v(_v), j(_j) { }
     37:   __host__ __device__ void operator()(PetscInt i) { v[i] = (i == j ? 1 : 0); }
     38: };
     39: #endif

     41: PETSC_INTERN PetscErrorCode VecSetDelta(Vec x, PetscInt i)
     42: {
     43: #if defined(PETSC_HAVE_CUDA)
     44:   PetscBool iscuda;
     45: #endif
     46:   PetscInt st, en;

     48:   PetscFunctionBegin;
     49:   PetscCall(VecGetOwnershipRange(x, &st, &en));
     50: #if defined(PETSC_HAVE_CUDA)
     51:   PetscCall(PetscObjectTypeCompareAny((PetscObject)x, &iscuda, VECSEQCUDA, VECMPICUDA, ""));
     52:   iscuda = (PetscBool)(iscuda && !x->boundtocpu);
     53:   if (iscuda) {
     54:     PetscScalar *ax;
     55:     PetscCall(VecCUDAGetArrayWrite(x, &ax));
     56:     StandardBasis_Functor delta(ax, i - st);
     57:     thrust::for_each(thrust::device, thrust::counting_iterator<PetscInt>(0), thrust::counting_iterator<PetscInt>(en - st), delta);
     58:     PetscCall(VecCUDARestoreArrayWrite(x, &ax));
     59:   } else
     60: #endif
     61:   {
     62:     PetscCall(VecSet(x, 0.));
     63:     if (st <= i && i < en) PetscCall(VecSetValue(x, i, 1.0, INSERT_VALUES));
     64:     PetscCall(VecAssemblyBegin(x));
     65:     PetscCall(VecAssemblyEnd(x));
     66:   }
     67:   PetscFunctionReturn(PETSC_SUCCESS);
     68: }

     70: /* these are approximate norms */
     71: /* NORM_2: Estimating the matrix p-norm Nicholas J. Higham
     72:    NORM_1/NORM_INFINITY: A block algorithm for matrix 1-norm estimation, with an application to 1-norm pseudospectra Higham, Nicholas J. and Tisseur, Francoise */
     73: PETSC_INTERN PetscErrorCode MatApproximateNorm_Private(Mat A, NormType normtype, PetscInt normsamples, PetscReal *n)
     74: {
     75:   Vec         x, y, w, z;
     76:   PetscReal   normz, adot;
     77:   PetscScalar dot;
     78:   PetscInt    i, j, N, jold = -1;
     79:   PetscBool   boundtocpu = PETSC_TRUE;

     81:   PetscFunctionBegin;
     82: #if defined(PETSC_HAVE_DEVICE)
     83:   boundtocpu = A->boundtocpu;
     84: #endif
     85:   switch (normtype) {
     86:   case NORM_INFINITY:
     87:   case NORM_1:
     88:     if (normsamples < 0) normsamples = 10; /* pure guess */
     89:     if (normtype == NORM_INFINITY) {
     90:       Mat B;
     91:       PetscCall(MatCreateTranspose(A, &B));
     92:       A = B;
     93:     } else {
     94:       PetscCall(PetscObjectReference((PetscObject)A));
     95:     }
     96:     PetscCall(MatCreateVecs(A, &x, &y));
     97:     PetscCall(MatCreateVecs(A, &z, &w));
     98:     PetscCall(VecBindToCPU(x, boundtocpu));
     99:     PetscCall(VecBindToCPU(y, boundtocpu));
    100:     PetscCall(VecBindToCPU(z, boundtocpu));
    101:     PetscCall(VecBindToCPU(w, boundtocpu));
    102:     PetscCall(VecGetSize(x, &N));
    103:     PetscCall(VecSet(x, 1. / N));
    104:     *n = 0.0;
    105:     for (i = 0; i < normsamples; i++) {
    106:       PetscCall(MatMult(A, x, y));
    107:       PetscCall(VecPointwiseSign(w, y, VEC_SIGN_ZERO_TO_SIGNED_UNIT));
    108:       PetscCall(MatMultTranspose(A, w, z));
    109:       PetscCall(VecNorm(z, NORM_INFINITY, &normz));
    110:       PetscCall(VecDot(x, z, &dot));
    111:       adot = PetscAbsScalar(dot);
    112:       PetscCall(PetscInfo(A, "%s norm it %" PetscInt_FMT " -> (%g %g)\n", NormTypes[normtype], i, (double)normz, (double)adot));
    113:       if (normz <= adot && i > 0) {
    114:         PetscCall(VecNorm(y, NORM_1, n));
    115:         break;
    116:       }
    117:       PetscCall(VecMax(z, &j, &normz));
    118:       if (j == jold) {
    119:         PetscCall(VecNorm(y, NORM_1, n));
    120:         PetscCall(PetscInfo(A, "%s norm it %" PetscInt_FMT " -> breakdown (j==jold)\n", NormTypes[normtype], i));
    121:         break;
    122:       }
    123:       jold = j;
    124:       PetscCall(VecSetDelta(x, j));
    125:     }
    126:     PetscCall(MatDestroy(&A));
    127:     PetscCall(VecDestroy(&x));
    128:     PetscCall(VecDestroy(&w));
    129:     PetscCall(VecDestroy(&y));
    130:     PetscCall(VecDestroy(&z));
    131:     break;
    132:   case NORM_2:
    133:     if (normsamples < 0) normsamples = 20; /* pure guess */
    134:     PetscCall(MatCreateVecs(A, &x, &y));
    135:     PetscCall(MatCreateVecs(A, &z, NULL));
    136:     PetscCall(VecBindToCPU(x, boundtocpu));
    137:     PetscCall(VecBindToCPU(y, boundtocpu));
    138:     PetscCall(VecBindToCPU(z, boundtocpu));
    139:     PetscCall(VecSetRandom(x, NULL));
    140:     PetscCall(VecNormalize(x, NULL));
    141:     *n = 0.0;
    142:     for (i = 0; i < normsamples; i++) {
    143:       PetscCall(MatMult(A, x, y));
    144:       PetscCall(VecNormalize(y, n));
    145:       PetscCall(MatMultTranspose(A, y, z));
    146:       PetscCall(VecNorm(z, NORM_2, &normz));
    147:       PetscCall(VecDot(x, z, &dot));
    148:       adot = PetscAbsScalar(dot);
    149:       PetscCall(PetscInfo(A, "%s norm it %" PetscInt_FMT " -> %g (%g %g)\n", NormTypes[normtype], i, (double)*n, (double)normz, (double)adot));
    150:       if (normz <= adot) break;
    151:       if (i < normsamples - 1) {
    152:         Vec t;

    154:         PetscCall(VecNormalize(z, NULL));
    155:         t = x;
    156:         x = z;
    157:         z = t;
    158:       }
    159:     }
    160:     PetscCall(VecDestroy(&x));
    161:     PetscCall(VecDestroy(&y));
    162:     PetscCall(VecDestroy(&z));
    163:     break;
    164:   default:
    165:     SETERRQ(PetscObjectComm((PetscObject)A), PETSC_ERR_SUP, "%s norm not supported", NormTypes[normtype]);
    166:   }
    167:   PetscCall(PetscInfo(A, "%s norm %g computed in %" PetscInt_FMT " iterations\n", NormTypes[normtype], (double)*n, i));
    168:   PetscFunctionReturn(PETSC_SUCCESS);
    169: }