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

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