SMATH struggles to perform a Filon Fourier Transform versus MATHCAD 15. See attached SMATH worksheet. With the current settings, it takes about a minute to run. Press F9 to run. Notice comments included in the worksheet.

FILON DEVELOLPMENT.sm (175 KiB) downloaded 73 time(s).

I wish it were no so because MATHCAD 15 is no longer available or supported.