/*****************************************************************************
*                                                                            *
*   VALFILL.SPL  Copyright (C) 1999 DSP Development Corporation              *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Replaces a value with previous or next value                *
*                                                                            *
*   Revisions:   14 May 1999  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/

#include 

#if @HELP_VALFILL

    VALFILL

    Purpose: Replaces a value with previous or next value

    Syntax:  VALFILL(s, val, mode)

              s    - a series or array, the input data

              val  - an optional real, value to replace, defaults to 0.0

              mode - an optional integer, fill mode:
                     0: no fill,
                     1: fill forward using last know value
                     2: fill forward then backward
                     3: fill backward then forward

                     defaults to 2


    Returns: A series or array

    Example:
             W1: Ravel(gnorm(100, 1), 10)
             W2: (W1 > 0.4) * W1
             W3: Valfill(W2)


             The zeros of W2 are replaced with the last known
             value by first searching forward in each column and
             then searching backwards.

    Remarks:

             VALFIL is based on NAFILL.

    See Also:
             Nafill
#endif


/* replaces values is a series with last known value */
valfill(s, val, mode)
{
        local array;

        if (argc < 3)
        {
                if (argc < 2)
                {
                        if (argc < 1) error("fillval - input series required");
                        
                        val = 0.0;
                }
                
                mode = 2;
        }

        /* replace val with NA in array */
        array = s;
        array[find(s == val)] = navalue;

        /* now fill NA's based on mode */
        array = nafill(array, mode);

        return(array);
}