/*****************************************************************************
*                                                                            *
*   GDAMPSIN.SPL Copyright (C) 2024 DSP Development Corporation              *
*                               All Rights Reserved                          *
*                                                                            *
*   Author:      Randy Race                                                  *
*                                                                            *
*   Synopsis:    Generates a damped sinewave                                 *
*                                                                            *
*   Revisions:    5 Sep 2024  RRR  Creation                                  *
*                                                                            *
*****************************************************************************/


#if @HELP_GDAMPSIN

    GDAMPSIN

    Purpose:
             Generates a damped sinewave.

    Syntax:
             GDAMPSIN(length, spacing, frequency, phase, dampfac)

                length  - An integer, the number of points to generate.

                spacing - A real, the spacing (deltax) between points.

              frequency - Optional. A real, the frequency in Hertz.
                          Defaults to 10 Hz.

                  phase - Optional. A real, the phase specified in radians.
                          Defaults to 0.

                 dampfac - Optional. A real, the exponential damping factor.
                           Defaults to -5.0.

    Returns:
             A series, an exponentially damped sinewave.

    Example:
             W1: gdampsin(1000, 0.001)

             Creates a 1000 point 10 Hz damped sinewave with points spaced at
             an interval of 0.001 seconds (a sample rate of 1000 Hz) with a
             phase of 0 and a damping factor of -5.0.

    Example:
             W2: gdampsin(1000, 0.001, 10, 0, -5)

             Same as above.

    Example:
             W3: 100*gdampsin(10000, 1/1000, 5, 0, -0.5) + 50

             Generates 10000 samples of a 5 Hz damped sinewave sampled at
             1 kHz with a damping factor of -0.5. The amplitude is 100 and
             the result is offset by 50.0.
 
    Remarks:
             GDAMPSIN returns an exponentially damped sinewave.

             If DAMPFAC is positive, the series amplitude grows with time.

    See Also:
             Gsin
             Gsweep
#endif


/* generate an exponentially damped sinewave */
gdampsin(n=1000, dx=1/n, f=10, phi=0, b=-5)
{
        local s;

        s = gsin(n, dx, f, phi) * gexp(n, dx, b);

        return(s);
}