What is normally done using mechanical pendulums can also be done on a spread sheet. If the spread sheet also provides the slider function, this can provide much greater controls over the various pendulum parameters.
The spreadsheet in OpenOffice does provide a working slider control which can set the value of a given cell.
The slider can also be stepped by smaller units for some precision adjustments.
This is a simplified mechanical pendulum simulation which graphs the X/Y points
In this case the X values has frequency, magnitude, decay, and phase parameters which follows this equation.
X = Magnitude*Exp(-time/decay_rate)*sin(2pi*frequency*time + PhaseShift*time)
Of course the equations need not be limited to this simple example.
The slider controls provide instance feedback as to what each parameter is doing.
Both the OpenOffice and Excel version are included. The Excel version unfortunately appears to have problems getting its slider controls to work properly, at least on a MacBookPro. If you download the Openoffice version, the file's extension my need to be changed to something like "FWVEAA8FR123iEH.ods".