SRC/dla_porcond.f(3)

NAME
SRC/dla_porcond.f

SYNOPSIS

  Functions/Subroutines
double precision function dla_porcond (uplo, n, a, lda, af, ldaf, cmode, c, info, work, iwork)
DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Function/Subroutine Documentation

  double precision function dla_porcond (character uplo, integer n, double precision, dimension( lda, * ) a, integer lda, double precision, dimension( ldaf, * ) af, integer ldaf, integer cmode, double precision, dimension( * ) c, integer info, double precision, dimension( * ) work, integer, dimension( * ) iwork)

DLA_PORCOND estimates the Skeel condition number for a symmetric positive-definite matrix.

Purpose:

    !>
    !>    DLA_PORCOND Estimates the Skeel condition number of  op(A) * op2(C)
    !>    where op2 is determined by CMODE as follows
    !>    CMODE =  1    op2(C) = C
    !>    CMODE =  0    op2(C) = I
    !>    CMODE = -1    op2(C) = inv(C)
    !>    The Skeel condition number  cond(A) = norminf( |inv(A)||A| )
    !>    is computed by computing scaling factors R such that
    !>    diag(R)*A*op2(C) is row equilibrated and computing the standard
    !>    infinity-norm condition number.
    !>

Parameters
    UPLO

    !>          UPLO is CHARACTER*1
    !>       = 'U':  Upper triangle of A is stored;
    !>       = 'L':  Lower triangle of A is stored.
    !>

    N

    !>          N is INTEGER
    !>     The number of linear equations, i.e., the order of the
    !>     matrix A.  N >= 0.
    !>

    A

    !>          A is DOUBLE PRECISION array, dimension (LDA,N)
    !>     On entry, the N-by-N matrix A.
    !>

    LDA

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

    AF

    !>          AF is DOUBLE PRECISION array, dimension (LDAF,N)
    !>     The triangular factor U or L from the Cholesky factorization
    !>     A = U**T*U or A = L*L**T, as computed by DPOTRF.
    !>

    LDAF

    !>          LDAF is INTEGER
    !>     The leading dimension of the array AF.  LDAF >= max(1,N).
    !>

    CMODE

    !>          CMODE is INTEGER
    !>     Determines op2(C) in the formula op(A) * op2(C) as follows:
    !>     CMODE =  1    op2(C) = C
    !>     CMODE =  0    op2(C) = I
    !>     CMODE = -1    op2(C) = inv(C)
    !>

    C

    !>          C is DOUBLE PRECISION array, dimension (N)
    !>     The vector C in the formula op(A) * op2(C).
    !>

    INFO

    !>          INFO is INTEGER
    !>       = 0:  Successful exit.
    !>     i > 0:  The ith argument is invalid.
    !>

    WORK

    !>          WORK is DOUBLE PRECISION array, dimension (3*N).
    !>     Workspace.
    !>

    IWORK

    !>          IWORK is INTEGER array, dimension (N).
    !>     Workspace.
    !>

Author
    Univ. of Tennessee

    Univ. of California Berkeley

    Univ. of Colorado Denver

    NAG Ltd.

Definition at line 139 of file dla_porcond.f.

Author

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