pure functiondgecon

Information

Lapack documentation
    Purpose
    =======

    DGECON estimates the reciprocal of the condition number of a general
    real matrix A, in either the 1-norm or the infinity-norm, using
    the LU factorization computed by DGETRF.

    An estimate is obtained for norm(inv(A)), and 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.

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

    A       (input) DOUBLE PRECISION array, dimension (LDA,N)
            The factors L and U from the factorization A = P*L*U
            as computed by DGETRF.

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

    ANORM   (input) DOUBLE PRECISION
            If NORM = '1' or 'O', the 1-norm of the original matrix A.
            If NORM = 'I', the infinity-norm of the original matrix A.

    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 (4*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

Inputs

Outputs