1: #include <petsc/private/randomimpl.h>
  2: #include <thrust/tuple.h>
  3: #include <thrust/transform.h>
  4: #include <thrust/device_ptr.h>
  5: #include <thrust/iterator/counting_iterator.h>

  7: #if PetscDefined(USE_COMPLEX)
  8: struct complexscalelw {
  9:   PetscReal rl, rw;
 10:   PetscReal il, iw;

 12:   complexscalelw(PetscScalar low, PetscScalar width)
 13:   {
 14:     rl = PetscRealPart(low);
 15:     il = PetscImaginaryPart(low);
 16:     rw = PetscRealPart(width);
 17:     iw = PetscImaginaryPart(width);
 18:   }

 20:   __host__ __device__ PetscReal operator()(thrust::tuple<PetscReal, size_t> x) { return thrust::get<1>(x) % 2 ? thrust::get<0>(x) * iw + il : thrust::get<0>(x) * rw + rl; }
 21: };
 22: #endif

 24: struct realscalelw {
 25:   PetscReal l, w;

 27:   realscalelw(PetscReal low, PetscReal width) : l(low), w(width) { }

 29:   __host__ __device__ PetscReal operator()(PetscReal x) { return x * w + l; }
 30: };

 32: PETSC_INTERN PetscErrorCode PetscRandomCurandScale_Private(PetscRandom r, size_t n, PetscReal *val, PetscBool isneg)
 33: {
 34:   PetscFunctionBegin;
 35:   if (!r->iset) PetscFunctionReturn(PETSC_SUCCESS);
 36:   if (isneg) { /* complex case, need to scale differently */
 37: #if PetscDefined(USE_COMPLEX)
 38:     thrust::device_ptr<PetscReal> pval  = thrust::device_pointer_cast(val);
 39:     auto                          zibit = thrust::make_zip_iterator(thrust::make_tuple(pval, thrust::counting_iterator<size_t>(0)));
 40:     thrust::transform(zibit, zibit + n, pval, complexscalelw(r->low, r->width));
 41: #else
 42:     SETERRQ(PETSC_COMM_SELF, PETSC_ERR_PLIB, "Negative array size %" PetscInt_FMT, (PetscInt)n);
 43: #endif
 44:   } else {
 45:     PetscReal                     rl   = PetscRealPart(r->low);
 46:     PetscReal                     rw   = PetscRealPart(r->width);
 47:     thrust::device_ptr<PetscReal> pval = thrust::device_pointer_cast(val);
 48:     thrust::transform(pval, pval + n, pval, realscalelw(rl, rw));
 49:   }
 50:   PetscFunctionReturn(PETSC_SUCCESS);
 51: }