/*****************************************************************************
*                                                                            *
*   RESCALE.SPL  Copyright (C) 2001-2004 DSP Development Corporation         *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Linearly rescales an input series                           *
*                                                                            *
*   Revisions:   25 Jul 2001  RRR  Creation                                  *
*                10 Sep 2004  RRR  min/max instead of min/maxval for images  *
*                                                                            *
*****************************************************************************/

#include 

#if @HELP_RESCALE

    RESCALE

    Purpose: Linearly rescales an input series

    Syntax:  RESCALE(xi, yl, yh, xl, xh, clipflag)

                   xi  - input series or scalar

                   yl  - an optional real, low value output range,
                         defaults to 0.0

                   yh  - an optional real, high value output range,
                         defaults to 1.0

                   xl  - an optional real, low value input range,
                         defaults to minval(xi)

                   xh  - an optional real, high value input range.
                         defaults to maxval(xi)


              clipflag - an optional integer, 1:clip input
                         to xl and xh, 0:do not clip, defaults
                         to 1.

    Returns: A series or real

    Example:
             Rescale(10, -1, 1, 0, 100)

             returns -0.8, the corresponding output for an input
             value of 10.0 on a 0 to 100 input range and a
             corresponding -1.0 to 1.0 output range.

    Example:
             Rescale(0..100)

             returns a series ranging from 0 to 1. This is equivalent
             to:

             Rescale(0..100, 0, 1, 0, 100)

    Example:
             Rescale(0..100, -5, 5)

             returns a series ranging from -5 to 5. This is equivalent
             to:

             Rescale(0..100, -5, 5, 0, 100)

    Example:
             Rescale(0..100, -5, 5, -200, 200)

             returns a series ranging from 0 to 2.5


    Remarks:
             By default, Rescale automatically clips out of range
             input values. Rescale uses Linscale to lineraly convert
             the input values.

    See Also:
             Bitscale
             Linscale
             Quantize
#endif


/* linearly rescale input range to output range */
ITERATE rescale(xi, yl, yh, xl, xh, clipflag)
{
        local delta, xspan, yspan, yo;

        /* check input args */
        if (argc < 6)
        {
                if (argc < 5)
                {
                        if (argc < 4)
                        {
                                if (argc < 3)
                                {
                                        if (argc < 2)
                                        {
                                                if (argc < 1)
                                                {
                                                        error("rescale: input value required");
                                                }

                                                yl = 0.0;
                                        }

                                        yh = 1.0;
                                }

                                xl = min(xi);
                        }

                        xh = max(xi);
                }

                clipflag = 1;
        }

        /* linscale does the job */
        return(linscale(xi, xl, xh, yl, yh, clipflag));
}