This content has been marked as final.
Show 14 replies

Fourier transform of sin(Wt)
ptc1178444 Aug 16, 2002 12:00 AM (in response to ptc1218903)What version of Mathcad do you use?
Xavier 

Fourier transform of sin(Wt)
ptc1218903 Aug 16, 2002 12:00 AM (in response to ptc1178444)Hello Xavier
I am not vey familiar with symbolic calculation...just catching up. Appreciate if you can get me Mathcad file with this implemented.
Thanks for your help.
Regards
leyo Joseph
Fourier transform of sin(Wt)
ptc1178444 Aug 16, 2002 12:00 AM (in response to ptc1218903)Here is something in 2001i format.
Xavier
Fourier transform of sin(Wt)
ptc1218903 Aug 19, 2002 12:00 AM (in response to ptc1178444)Hello Xavier
I am unsing Mathcad 2000. Not able to open the Mathcad file in 2001 version you had posted. Appreciate if you can get me 2000 version.
Thanks
Leyo
Fourier transform of sin(Wt)
ptc1178444 Aug 19, 2002 12:00 AM (in response to ptc1218903)Here it is in 2000 format.
X
Fourier transform of sin(Wt)
ptc1218903 Aug 19, 2002 12:00 AM (in response to ptc1178444)Hello Xavier
Thanks... It works.
One more question please.
I have a function of time and want to plot the spectrum in frequency domain. Can I plot the symbolic calculated fourier function as function of (w)?.
Thanks
Leyo Joseph






Fourier transform of sin(Wt)
FredKohlhepp Aug 16, 2002 12:00 AM (in response to ptc1218903)Review the functions "fft", "ifft", "FFT", and "iFFT".
Fred Kohlhepp
fkohlhepp@sikorsky.com 
Fourier transform of sin(Wt)
ptc1178444 Aug 19, 2002 12:00 AM (in response to ptc1218903)That's where it gets ugly really fast! A distribution such as the Dirac distribution cannot be plotted as easily as a function. JMG showed examples in this thread where the Fourier transform has a usable close form.
The rest of the time you'll end up using a discrete Fourier transform calculation to display the function spectrum. Needless to say, one must be really careful about discrete sampling, windowing and aliasing effects...
If you have a specific function in mind we can certainly get you started.
Xavier
Fourier transform of sin(Wt)
ptc1368288 Aug 19, 2002 12:00 AM (in response to ptc1178444)Attached in 2000 is a tutorial about DFT and 'fft'. The overall presentation is not final but it contains lot of information and several examples.
_________DO NOT OPTIMIZE________
it will kill your box. It blocks at the definition of DFT and never stops and you can not stop calculating either !
It pushes the symbolic in corner.
Please confirm you can open.
Fourier transform of sin(Wt)
ptc1178444 Aug 20, 2002 12:00 AM (in response to ptc1368288)Nice worksheet, Jean.
One comment about the DFT: the advantage of the DFT is that it allows to calculate spectral components at any frequency, contrary to the FFT (given a fixed number of samples). The FFT is usefull to get a full spectrum sampling in one shot. The DFT allows to focus on a particular frequency.
Xavier



Fourier transform of sin(Wt)
ptc1368288 Aug 20, 2002 12:00 AM (in response to ptc1178444)Merci Xavier,
True, DFT is useful to have. The only problem is that it blocks dead the optimize and you have to crash the box.
Like Robert says: optimize => puzzling !
In the next posting, "Mathcad usage chat" I will attach 4 work sheets saved 2000 [Hope they open correct], then in one of them optimize does such a great job !