/*****************************************************************************
*                                                                            *
*   SONOGRAM.SPL   Copyright (C) 1997 DSP Development Corporation            *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Calculates and plots the magnitude of the STFT as a         *
*                Black on White image                                        *
*                                                                            *
*   Revisions:    9 Jul 1997  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/


#if @HELP_SONOGRAM

    SONOGRAM

    Purpose: Calculates the 2D Spectrogram as a B&W image.

    Syntax:  SONOGRAM(series, len, lap, swin)

                 series  -    input series
                    len  -    FFT length
                    lap  -    optional overlap length, defaults to len / 2
                   swin  -    optional windowing function, default HAMMING


    Returns: A table of Amplitude values in Frequency vs Time format.

    Example:
             SONOGRAM(W1, 128)

             Divides W1 into columns of 128 points that overlap by 64
             points. The Spectrum (i.e. magnitude of the FFT) of each
             column is calculated and the result is displayed as an
             image. The image is displayed as Black on White.

     Remarks:
             The following windows are offered:
             0:Hamming, 1:Hanning, 2:Rectangle (none) 3:Kaiser

     See Also:

             FFT
             Ravel
             Specgram
             Spectrum

#endif



/* Magnitude of Short Term Fourier Transform as Density plot */
sonogram(s, len, lap, swin)
{
        if (outargc == 0)
        {
                setshading("white", "black");
                specgram(s, len, lap, int(len / 2), swin);
        }
        else
        {
                return(specgram(s, len, lap, int(len / 2), swin));
        }
}