TESTING/LIN/dtrt02.f(3)    Library Functions Manual    TESTING/LIN/dtrt02.f(3)

NAME
       TESTING/LIN/dtrt02.f

SYNOPSIS
   Functions/Subroutines
       subroutine dtrt02 (uplo, trans, diag, n, nrhs, a, lda, x, ldx, b, ldb,
           work, resid)
           DTRT02

Function/Subroutine Documentation
   subroutine dtrt02 (character uplo, character trans, character diag, 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( * )
       work, double precision resid)
       DTRT02

       Purpose:


            DTRT02 computes the residual for the computed solution to a
            triangular system of linear equations op(A)*X = B, where A is a
            triangular matrix. The test ratio is the maximum over
               norm(b - op(A)*x) / ( ||op(A)||_1 * norm(x) * EPS ),
            where op(A) = A or A**T, b is the column of B, x is the solution
            vector, and EPS is the machine epsilon.
            The norm used is the 1-norm.

       Parameters
           UPLO

                     UPLO is CHARACTER*1
                     Specifies whether the matrix A is upper or lower triangular.
                     = 'U':  Upper triangular
                     = 'L':  Lower triangular

           TRANS

                     TRANS is CHARACTER*1
                     Specifies the operation applied to A.
                     = 'N':  A    * X = B  (No transpose)
                     = 'T':  A**T * X = B  (Transpose)
                     = 'C':  A**H * X = B  (Conjugate transpose = Transpose)

           DIAG

                     DIAG is CHARACTER*1
                     Specifies whether or not the matrix A is unit triangular.
                     = 'N':  Non-unit triangular
                     = 'U':  Unit triangular

           N

                     N is INTEGER
                     The order of the matrix A.  N >= 0.

           NRHS

                     NRHS is INTEGER
                     The number of right hand sides, i.e., the number of columns
                     of the matrices X and B.  NRHS >= 0.

           A

                     A is DOUBLE PRECISION array, dimension (LDA,N)
                     The triangular matrix A.  If UPLO = 'U', the leading n by n
                     upper triangular part of the array A contains the upper
                     triangular matrix, and the strictly lower triangular part of
                     A is not referenced.  If UPLO = 'L', the leading n by n lower
                     triangular part of the array A contains the lower triangular
                     matrix, and the strictly upper triangular part of A is not
                     referenced.  If DIAG = 'U', the diagonal elements of A are
                     also not referenced and are assumed to be 1.

           LDA

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

           X

                     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

                     B is DOUBLE PRECISION array, dimension (LDB,NRHS)
                     The right hand side vectors for the system of linear
                     equations.

           LDB

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

           WORK

                     WORK is DOUBLE PRECISION array, dimension (N)

           RESID

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

       Author
           Univ. of Tennessee

           Univ. of California Berkeley

           Univ. of Colorado Denver

           NAG Ltd.

       Definition at line 148 of file dtrt02.f.

Author
       Generated automatically by Doxygen for LAPACK from the source code.

LAPACK                          Version 3.12.0         TESTING/LIN/dtrt02.f(3)