| dfourt [message #90829] |
Tue, 21 April 2015 16:35  |
beppe89
Messages: 1
Registered: April 2015
|
Junior Member |
|
|
Hi everyone,
I am a beginner in the use of IDL and and I need some help. I need to write a program that calculates the inverse of the discrete fourier transform calculated by the dfourt.pro.
I know that dft.pro calculates the inverse, but I really need the one from dfourt.pro.
Thanks,
--
beppe89
http://compgroups.net/comp.lang.idl-pvwave/
|
|
|
|
| Re: dfourt [message #90833 is a reply to message #90829] |
Fri, 24 April 2015 11:44  |
Matthew Argall
Messages: 286
Registered: October 2011
|
Senior Member |
|
|
Looking at the code
http://www.arm.ac.uk/~csj/idl/CLEAN/dfourt.pro
It seems pretty easy to do. They appear to be building the Fourier transform as described in any undergraduate mathematical methods text (e.g. Boas). Essentially, the inverse transform would be
ifft = complex(0, 0)
for i = 0, npts - 1
ifft = ifft + complex( A[i] * cos(f[i]*t), B[i] * sin(f[i]*t)
endfor
Where A and B are the real and complex fourier coefficients, t is time, and f is frequency.
|
|
|
|
comp.lang.idl-pvwave archive
Members
Search
Help
Login
Home
