dget08.f3

Usage

Functions/Subroutines

subroutine dget08 (trans, m, n, nrhs, a, lda, x, ldx, b, ldb, rwork, resid)
DGET08

Function/Subroutine Documentation

subroutine dget08 (character trans, integer m, integer n, integer nrhs, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( * ) rwork, double precision resid)

DGET08

Purpose:

!>
!> DGET08 computes the residual for a solution of a system of linear
!> equations  A*x = b  or  A'*x = b:
!>    RESID = norm(B - A*X,inf) / ( norm(A,inf) * norm(X,inf) * EPS ),
!> where EPS is the machine epsilon.
!>

Parameters

TRANS

!>          TRANS is CHARACTER*1
!>          Specifies the form of the system of equations:
!>          = 'N':  A *x = b
!>          = 'T':  A'*x = b, where A' is the transpose of A
!>          = 'C':  A'*x = b, where A' is the transpose of A
!>

!>          M is INTEGER
!>          The number of rows of the matrix A.  M >= 0.
!>

!>          N is INTEGER
!>          The number of columns of the matrix A.  N >= 0.
!>

NRHS

!>          NRHS is INTEGER
!>          The number of columns of B, the matrix of right hand sides.
!>          NRHS >= 0.
!>

!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          The original M x N matrix A.
!>

LDA

!>          LDA is INTEGER
!>          The leading dimension of the array A.  LDA >= max(1,M).
!>

!>          X is DOUBLE PRECISION array, dimension (LDX,NRHS)
!>          The computed solution vectors for the system of linear
!>          equations.
!>

LDX

!>          LDX is INTEGER
!>          The leading dimension of the array X.  If TRANS = 'N',
!>          LDX >= max(1,N); if TRANS = 'T' or 'C', LDX >= max(1,M).
!>

!>          B is DOUBLE PRECISION array, dimension (LDB,NRHS)
!>          On entry, the right hand side vectors for the system of
!>          linear equations.
!>          On exit, B is overwritten with the difference B - A*X.
!>

LDB

!>          LDB is INTEGER
!>          The leading dimension of the array B.  IF TRANS = 'N',
!>          LDB >= max(1,M); if TRANS = 'T' or 'C', LDB >= max(1,N).
!>

RWORK

!>          RWORK is DOUBLE PRECISION array, dimension (M)
!>

RESID

!>          RESID is DOUBLE PRECISION
!>          The maximum over the number of right hand sides of
!>          norm(B - A*X) / ( norm(A) * norm(X) * EPS ).
!>

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line 131 of file dget08.f.