Parallel Engineering and Scientific Subroutine Library for AIX Version 2 Release 3: Guide and Reference

PGEASB--Assembles a Dense Vector

This sparse utility subroutine assembles a dense vector.

Syntax

On Entry

x

is a pointer to the local part of the dense vector that is produced by previous call(s) to PGEINS.

Scope: local

Type: required

Specified as: a pointer to an assumed-shape array with shape (:), containing long-precision real numbers.

desc_a

is the array descriptor, which was finalized in a preceding call to PSPASB.

Type: required

Specified as: the derived data type DESC_TYPE.

On Return

x

is a pointer to the local part of the global dense vector.

Scope: local

Type: required

Returned as: a pointer to an assumed-sized array with shape (:), containing long-precision real numbers.

Notes and Coding Rules

1. Before you call this subroutine, you must have called PGEINS as many times as needed; that is, you must have completed building the dense vectors with call(s) to PGEINS before you place a call to this subroutine.

   Before you call this subroutine, you must have called PSPASB.

2. You do not need a separate array descriptor for a dense vector because it must conform to the size of matrix A. For details about some of the elements stored in DESC_A%MATRIX_DATA, see Derived Data Type DESC_TYPE.
3. This subroutine must be called for:
   • Vector b containing the right-hand side.
   • Vector x containing the initial guess to the solution.

Error Conditions

Computational Errors

None

Resource Errors

None.

Input-Argument and Miscellaneous Errors

Stage 1:  

1. desc_a has not been initialized.

Stage 2:  

1. The BLACS context is invalid.

Stage 3:  

1. This subroutine was called from outside the process grid.

Stage 4:  

1. The process grid is not np × 1.
2. desc_a component(s) are not valid.
3. size(x,1) < DESC_A%MATRIX_DATA(N_ROW)