[Numpy-discussion] Normalization of ifft

Gideon Simpson simpson@math.toronto....
Thu Mar 26 21:02:26 CDT 2009


I thought it was the same as the MATLAB format:

http://www.mathworks.com/access/helpdesk/help/techdoc/index.html?/access/helpdesk/help/techdoc/ref/fft.html&http://www.google.com/search 
?client=safari&rls=en-us&q=MATLAB+fft&ie=UTF-8&oe=UTF-8

On Mar 26, 2009, at 7:56 PM, Lutz Maibaum wrote:

> Hello,
>
> I just started to use python and numpy for some numerical analysis. I
> have a question about the definition of the inverse Fourier transform.
> The user gives the formula (p.180)
>
>  x[m] = Sum_k X[k] exp(j 2pi k m / n)
>
> where X[k] are the Fourier coefficients, and n is the length of the  
> arrays.
>
> The online documentation
> (http://docs.scipy.org/doc/numpy/reference/routines.fft.html), on the
> other hand, states that there is an additional factor of 1/n, which is
> required to make ifft() the inverse of fft(). Is this a misprint in
> the user guide?
>
>  Lutz
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-gideon



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