5.5 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 5.3 and 5.4 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

x

type(kind_parameter), dimension(:), intent(in)—.

The local part of the vector x. Note that type and kind_parameter must be chosen according to the real/complex, single/double precision version of AMG4PSBLAS under use.

y

type

a

type(psb_xspmat_type), intent>>>>>> development class="cmtt-12">(in).

The local part of the vector y. Note that type and kind_parameter ======= style="vertical-align:baseline;" id="TBL-13-2-">

The sparse matrix structure containing the local part of the matrix >>>>>>> development 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 [20].

desc_a

desc_a

>>>>>> development class="cmtt-12">type(psb_desc_type), intent(in).

The communication descriptor associated to the matrix to be ======= style="vertical-align:baseline;" id="TBL-13-4-">

The communication descriptor of a. See the PSBLAS User’s Guide >>>>>>> development for details [20].

info

info

>>>>>> development class="cmtt-12">integer, intent(out).

>>>>>> development class="cmr-12">Error code. If no error, 0 is returned. See Section 7 for details.

trans

character

amold

class>>>>>> development class="cmtt-12">(psb_x_base_sparse_mat), intent(in), optional.

If trans = N,n then op(B-1) = B-1; if trans = T,t ======= style="vertical-align:baseline;" id="TBL-13-8-">

The desired dynamic type for internal matrix components; this >>>>>>> development allows e.g. running on GPUs; it needs not be the same on all processes. See the PSBLAS User’s Guide for details [20].

work

type(kind_parameter), dimension(:), optional, target—.

Workspace. Its size should be at least 4 *

vmold

class(psb_x_base_vect_type),>>>>>> development class="cmtt-12"> 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.

>>>>>> development class="td11">

The method can be used to build multilevel preconditioners too.