6.5 Method build

call p%build(a,desc_a,info[,amold,vmold,imold])

This method builds the preconditioner p according to the requirements made by the user through the methods init and set (see Sections 6.3 and 6.4 for multilevel preconditioners). It is mostly provided for backward compatibility; indeed, it is internally implemented by invoking the two previous methods hierarchy_build and smoothers_build, whose nomenclature would however be somewhat unnatural when dealing with simple one-level preconditioners.

Arguments

a

type(psb_xspmat_type), intent(in).

The sparse matrix structure containing the local part of the matrix to be preconditioned. Note that x must be chosen according to the real/complex, single/double precision version of AMG4PSBLAS under use. See the PSBLAS User’s Guide for details [16].

desc_a

type(psb_desc_type), intent(in).

The communication descriptor of a. See the PSBLAS User’s Guide for details [16].

info

integer, intent(out).

Error code. If no error, 0 is returned. See Section 8 for details.

amold

class(psb_x_base_sparse_mat), intent(in), optional.

The desired dynamic type for internal matrix components; this allows e.g. running on GPUs; it needs not be the same on all processes. See the PSBLAS User’s Guide for details [16].

vmold

class(psb_x_base_vect_type), intent(in), optional.

The desired dynamic type for internal vector components; this allows e.g. running on GPUs.

imold

class(psb_i_base_vect_type), intent(in), optional.

The desired dynamic type for internal integer vector components; this allows e.g. running on GPUs.

The method can be used to build multilevel preconditioners too.