1: #define PETSC_DESIRE_FEATURE_TEST_MACROS /* for drand48() */
  2: #include <petsc/private/randomimpl.h>

  4: static PetscErrorCode PetscRandomSeed_Rand48(PetscRandom r)
  5: {
  6:   PetscFunctionBegin;
  7:   srand48(r->seed);
  8:   PetscFunctionReturn(PETSC_SUCCESS);
  9: }

 11: static PetscErrorCode PetscRandomGetValue_Rand48(PetscRandom r, PetscScalar *val)
 12: {
 13:   PetscFunctionBegin;
 14: #if defined(PETSC_USE_COMPLEX)
 15:   if (r->iset) {
 16:     *val = PetscRealPart(r->width) * (PetscReal)drand48() + PetscRealPart(r->low) + (PetscImaginaryPart(r->width) * (PetscReal)drand48() + PetscImaginaryPart(r->low)) * PETSC_i;
 17:   } else {
 18:     *val = (PetscReal)drand48() + (PetscReal)drand48() * PETSC_i;
 19:   }
 20: #else
 21:   if (r->iset) *val = r->width * drand48() + (PetscReal)r->low;
 22:   else *val = drand48();
 23: #endif
 24:   PetscFunctionReturn(PETSC_SUCCESS);
 25: }

 27: static PetscErrorCode PetscRandomGetValueReal_Rand48(PetscRandom r, PetscReal *val)
 28: {
 29:   PetscFunctionBegin;
 30: #if defined(PETSC_USE_COMPLEX)
 31:   if (r->iset) *val = PetscRealPart(r->width) * drand48() + PetscRealPart(r->low);
 32:   else *val = drand48();
 33: #else
 34:   if (r->iset) *val = r->width * (PetscReal)drand48() + (PetscReal)r->low;
 35:   else *val = (PetscReal)drand48();
 36: #endif
 37:   PetscFunctionReturn(PETSC_SUCCESS);
 38: }

 40: static struct _PetscRandomOps PetscRandomOps_Values = {
 41:   PetscDesignatedInitializer(seed, PetscRandomSeed_Rand48),
 42:   PetscDesignatedInitializer(getvalue, PetscRandomGetValue_Rand48),
 43:   PetscDesignatedInitializer(getvaluereal, PetscRandomGetValueReal_Rand48),
 44:   PetscDesignatedInitializer(getvalues, NULL),
 45:   PetscDesignatedInitializer(getvaluesreal, NULL),
 46:   PetscDesignatedInitializer(destroy, NULL),
 47:   PetscDesignatedInitializer(setfromoptions, NULL),
 48: };

 50: /*MC
 51:    PETSCRAND48 - access to the basic Unix `drand48()` random number generator

 53:    Options Database Key:
 54: . -random_type <rand,rand48,sprng> - select the random number generator at runtime

 56:   Level: beginner

 58:   Note:
 59:   Not recommended because it may produce different results on different systems.

 61: .seealso: `PetscRandomCreate()`, `PetscRandomSetType()`, `PETSCRAND`, `PETSCSPRNG`, `PetscRandomSetFromOptions()`
 62: M*/

 64: PETSC_EXTERN PetscErrorCode PetscRandomCreate_Rand48(PetscRandom r)
 65: {
 66:   PetscFunctionBegin;
 67:   r->ops[0] = PetscRandomOps_Values;
 68:   PetscCall(PetscObjectChangeTypeName((PetscObject)r, PETSCRAND48));
 69:   PetscFunctionReturn(PETSC_SUCCESS);
 70: }