Provided by: liblapack-doc_3.3.1-1_all bug

NAME

       LAPACK-3  -  estimates the reciprocal of the condition number of a triangular matrix A, in
       either the 1-norm or the infinity-norm

SYNOPSIS

       SUBROUTINE DTRCON( NORM, UPLO, DIAG, N, A, LDA, RCOND, WORK, IWORK, INFO )

           CHARACTER      DIAG, NORM, UPLO

           INTEGER        INFO, LDA, N

           DOUBLE         PRECISION RCOND

           INTEGER        IWORK( * )

           DOUBLE         PRECISION A( LDA, * ), WORK( * )

PURPOSE

       DTRCON estimates the reciprocal of the condition number  of  a  triangular  matrix  A,  in
       either the 1-norm or the infinity-norm.
        The norm of A is computed and an estimate is obtained for
        norm(inv(A)), then the reciprocal of the condition number is
        computed as
           RCOND = 1 / ( norm(A) * norm(inv(A)) ).

ARGUMENTS

        NORM    (input) CHARACTER*1
                Specifies whether the 1-norm condition number or the
                infinity-norm condition number is required:
                = '1' or 'O':  1-norm;
                = 'I':         Infinity-norm.

        UPLO    (input) CHARACTER*1
                = 'U':  A is upper triangular;
                = 'L':  A is lower triangular.

        DIAG    (input) CHARACTER*1
                = 'N':  A is non-unit triangular;
                = 'U':  A is unit triangular.

        N       (input) INTEGER
                The order of the matrix A.  N >= 0.

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

        RCOND   (output) DOUBLE PRECISION
                The reciprocal of the condition number of the matrix A,
                computed as RCOND = 1/(norm(A) * norm(inv(A))).

        WORK    (workspace) DOUBLE PRECISION array, dimension (3*N)

        IWORK   (workspace) INTEGER array, dimension (N)

        INFO    (output) INTEGER
                = 0:  successful exit
                < 0:  if INFO = -i, the i-th argument had an illegal value

 LAPACK routine (version 3.2)               April 2011                            DTRCON(3lapack)