TESTING/LIN/strt03.f(3)

NAME
TESTING/LIN/strt03.f

SYNOPSIS

  Functions/Subroutines
subroutine strt03 (uplo, trans, diag, n, nrhs, a, lda, scale, cnorm, tscal, x, ldx, b, ldb, work, resid)
STRT03

Function/Subroutine Documentation

  subroutine strt03 (character uplo, character trans, character diag, integer n, integer nrhs, real, dimension( lda, * ) a, integer lda, real scale, real, dimension( * ) cnorm, real tscal, real, dimension( ldx, * ) x, integer ldx, real, dimension( ldb, * ) b, integer ldb, real, dimension( * ) work, real resid)

STRT03

Purpose:

    !>
    !> STRT03 computes the residual for the solution to a scaled triangular
    !> system of equations A*x = s*b  or  A'*x = s*b.
    !> Here A is a triangular matrix, A' is the transpose of A, s is a
    !> scalar, and x and b are N by NRHS matrices.  The test ratio is the
    !> maximum over the number of right hand sides of
    !>    norm(s*b - op(A)*x) / ( norm(op(A)) * norm(x) * EPS ),
    !> where op(A) denotes A or A' and EPS is the machine epsilon.
    !>

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 = s*b  (No transpose)
    !>          = 'T':  A'*x = s*b  (Transpose)
    !>          = 'C':  A'*x = s*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 REAL 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).
    !>

    SCALE

    !>          SCALE is REAL
    !>          The scaling factor s used in solving the triangular system.
    !>

    CNORM

    !>          CNORM is REAL array, dimension (N)
    !>          The 1-norms of the columns of A, not counting the diagonal.
    !>

    TSCAL

    !>          TSCAL is REAL
    !>          The scaling factor used in computing the 1-norms in CNORM.
    !>          CNORM actually contains the column norms of TSCAL*A.
    !>

    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)
    !>          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 REAL array, dimension (N)
    !>

    RESID

    !>          RESID is REAL
    !>          The maximum over the number of right hand sides of
    !>          norm(op(A)*x - s*b) / ( norm(op(A)) * norm(x) * EPS ).
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 167 of file strt03.f.

Author

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