/*****************************************************************************
*                                                                            *
*   RCOND.SPL    Copyright (C) 2011 DSP Development Corporation              *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Estimates the reciprocal condition number of a matrix       *
*                                                                            *
*   Revisions:   26 Aug 2011  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/


#if @HELP_RCOND

    RCOND

    Purpose: Estimates the reciprocal condition number of a matrix.

    Syntax:  RCOND(a, p)

              a - input matrix, defaults to the current series

    Returns: A real, the estimated reciprocal condition number.

    Example:
             W1: {{1, 2, 3},
                  {4, 5, 6},
                  {7, 8, 9}}

             W2: {{1, 2, 3},
                  {4, 5, 6},
                  {7, 8, 0}}


             rcond(W1) == 1.54198E-018

             rcond(W2) == 0.0193548

    Remarks:
             If the input array is well conditioned, the reciprocal
             condition number is near 1. If the input is ill
             conditioned, the reciprocal condition number is near 0.

             See COND to compute the condition number.

    See Also:
             Cond
             Norm
             Rcond
             Svd
#endif


static wl = "";

/* reciprocal condition number */
rcond(a)
{
        local r;

        if (argc < 1)
        {
                a = refseries(w0);
        }

        /* ensure series */
        a = castseries(a);

        /* suppress errors */
        wl = getconf("math_warning_level");
        setconf("math_warning_level", "-1");

        /* condition number */
        r = 1 / cond(a, 1);

        /* reset */
        setconf("math_warning_level", wl);
        wl = "";

        return(r);
}


/* error handling - reset warning level */
rcond_error(errnum, errmes)
{
        if (strlen(wl) != 0)
        {
                setconf("math_warning_level", wl);
                wl = "";
        }

        error(errmes)
}