| | /* damped.i */
local damped;
/* DOCUMENT damped.i --- compute and output damped sine waves
SEE ALSO: damped_wave, q_out
*/
func damped_wave(phase, Q)
/* DOCUMENT damped_wave(phase, Q)
returns a damped sine wave evaluated at PHASE, for quality factor Q.
(High Q means little damping.) The PHASE is 2*pi after one period of
the natural frequency of the oscillator. PHASE and Q must be
conformable arrays.
SEE ALSO: q_out
*/
{
nu = 0.5/Q;
omega = sqrt(1.-nu*nu);
return sin(omega*phase)*exp(-nu*phase); /* always zero at phase==0 */
}
func q_out(Q, file)
/* DOCUMENT q_out, Q, file
or q_out(Q, file)
Write the damped sine wave of quality factor Q to the FILE.
FILE may be either a filename, to create the file, or a file
object returned by an earlier create or q_out operation. If
q_out is invoked as a function, it returns the file object.
The external variable
theta
determines the phase points at which the damped sine wave is
evaluated; q_out will write two header lines, followed by
two columns, with one line for each element of the theta
array. The first column is theta; the second is
damped_wave(theta, Q).
If Q is an array, the two header lines and two columns will
be repeated for each element of Q.
SEE ALSO: damped_wave
*/
{
if (structof(file)==string) file = create(file);
n = numberof(Q);
for (i=1 ; i<=n ; ++i) { /* loop on elements of Q */
write, file, "Q = "+pr1(Q(i));
write, file, " theta amplitude";
write, file, theta, damped_wave(theta,Q(i));
}
return file;
}
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