TESTING/LIN/dtpt03.f(3)

NAME
TESTING/LIN/dtpt03.f

SYNOPSIS

  Functions/Subroutines
subroutine dtpt03 (uplo, trans, diag, n, nrhs, ap, scale, cnorm, tscal, x, ldx, b, ldb, work, resid)
DTPT03

Function/Subroutine Documentation

  subroutine dtpt03 (character uplo, character trans, character diag, integer n, integer nrhs, double precision, dimension( * ) ap, double precision scale, double precision, dimension( * ) cnorm, double precision tscal, double precision, dimension( ldx, * ) x, integer ldx, double precision, dimension( ldb, * ) b, integer ldb, double precision, dimension( * ) work, double precision resid)

DTPT03

Purpose:

    !>
    !> DTPT03 computes the residual for the solution to a scaled triangular
    !> system of equations A*x = s*b  or  A'*x = s*b  when the triangular
    !> matrix A is stored in packed format.  Here 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.
    !>

    AP

    !>          AP is DOUBLE PRECISION array, dimension (N*(N+1)/2)
    !>          The upper or lower triangular matrix A, packed columnwise in
    !>          a linear array.  The j-th column of A is stored in the array
    !>          AP as follows:
    !>          if UPLO = 'U', AP((j-1)*j/2 + i) = A(i,j) for 1<=i<=j;
    !>          if UPLO = 'L',
    !>             AP((j-1)*(n-j) + j*(j+1)/2 + i-j) = A(i,j) for j<=i<=n.
    !>

    SCALE

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

    CNORM

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

    TSCAL

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

    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 - 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 159 of file dtpt03.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.