spot02.f - Man Page

subroutine spot02 (uplo, n, nrhs, a, lda, x, ldx, b, ldb, rwork, resid)
SPOT02

SPOT02

Purpose:

 SPOT02 computes the residual for the solution of a symmetric system
 of linear equations  A*x = b:

    RESID = norm(B - A*X) / ( norm(A) * norm(X) * EPS ),

 where EPS is the machine epsilon.

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

          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

          A is REAL array, dimension (LDA,N)
          The original symmetric matrix A.

LDA

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

X

          X is REAL 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

          B is REAL 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 REAL array, dimension (N)

RESID

          RESID is REAL
          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 125 of file spot02.f.