dppt02.f3

Usage

Functions/Subroutines

subroutine dppt02 (uplo, n, nrhs, a, x, ldx, b, ldb, rwork, resid)
DPPT02

Function/Subroutine Documentation

subroutine dppt02 (character uplo, integer n, integer nrhs, double precision, dimension( * ) a, double precision, dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( * ) rwork, double precision resid)

DPPT02

Purpose:

!>
!> DPPT02 computes the residual in the solution of a symmetric system
!> of linear equations  A*x = b  when packed storage is used for the
!> coefficient matrix.  The ratio computed is
!>
!>    RESID = norm(B - A*X) / ( norm(A) * norm(X) * EPS),
!>
!> where EPS is the machine precision.
!>

Parameters

UPLO

!>          UPLO is CHARACTER*1
!>          Specifies whether the upper or lower triangular part of the
!>          symmetric matrix A is stored:
!>          = 'U':  Upper triangular
!>          = 'L':  Lower triangular
!>

!>          N is INTEGER
!>          The number of rows and 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 (N*(N+1)/2)
!>          The original symmetric matrix A, stored as a packed
!>          triangular matrix.
!>

!>          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.   LDX >= max(1,N).
!>

!>          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.  LDB >= max(1,N).
!>

RWORK

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

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 120 of file dppt02.f.