Hello,

I’m encountering strange issues on octave, with fft function. The problem occurs only on my computer, I tried several other, and everything seem good.

When I call **“fft”** function ( **fft (X, N)** ) with **N** superior to **X** length, the result seems to be random.

(reminder from help: *If N is larger than the dimension along which the FFT is calculated, then X is resized and padded with zeros.*)

My script for example:

val=sin(10*(0:0.1:1000));

l=length(val);

f=fft(val, l*2);

plot(real(f));

(the 4 plots below are 4 different execution of the script above)

I tried different octave version (repository debian-testing 5.2, snap version 5.2 & 6.1 ), the problem is still here.

On octave 4 (debian-stable) it was ok.

Could the problem come from signal package instead of octave ?

Maybe some low level driver problem ? (I don’t know if octave use some hardware acceleration for calculation or something like this…).

Or maybe I am the problem, with a wrong usage, but I don’t know where ?

Thank you !