PetscRealIntMultTruncate#

Computes the product of a positive PetscReal and a positive PetscInt and truncates the value to slightly less than the maximal possible value.

Synopsis#

static inline PetscInt PetscRealIntMultTruncate(PetscReal a, PetscInt b)

Not Collective; No Fortran Support

Returns the result as a PetscInt value.

Use PetscInt64Mult() to compute the product of two PetscInt as a PetscInt64.

Use PetscIntMultTruncate() to compute the product of two positive PetscInt and truncate to fit a PetscInt.

Use PetscIntMultError() to compute the product of two PetscInt if you wish to generate an error if the result will not fit in a PetscInt.

We currently assume that PetscInt addition can never overflow, this is obviously wrong but requires many more checks.

This is used where we compute approximate sizes for workspace and need to insure the workspace is index-able.

advanced