# [SciPy-User] Does/how does ifft expect frequencies (on x-axis)? Classic List Threaded 4 messages Open this post in threaded view
|

## [SciPy-User] Does/how does ifft expect frequencies (on x-axis)?

 I was trying to ifft a filter magnitude response that’s simply drawn into an array of filter length, e.g. 64 samples. So I have the array of 64 samples and this obviously means that the x-axis is in samples, not frequencies. ifft:ing this array does give me something that looks like the impulse response, but I didn’t give ifft any frequency data, just samples 0-64 in the x-axis. What I think I could’ve done is rather specify the magnitude response in 2D array or something so that the frequency runs from [0.0, 1.0] (0.5 corresponding to the Nyquist frequency) and then specify the magnitudes in 64 samples evenly spread on [0.0, 1.0], which is what I _intend_ with my array. So does ifft expect frequencies somehow or does it also work in the way that I used it, i.e. that the frequency response going into it is in samples rather than in frequencies? The functions I’m interested are any ifft in SciPy. _______________________________________________ SciPy-User mailing list [hidden email] https://mail.scipy.org/mailman/listinfo/scipy-user
Open this post in threaded view
|

## [SciPy-User] Difference equation to frequency response?

 What’s a simple way to get the frequency response of a filter that’s expressed as difference equation using SciPy?Such as this lowpass filter:https://kiritchatterjee.wordpress.com/2014/11/10/a-simple-digital-low-pass-filter-in-c/y[i] = b * x[i] + (1-b) * y[i-1]_______________________________________________ SciPy-User mailing list [hidden email] https://mail.scipy.org/mailman/listinfo/scipy-user