[SciPy-User] Help with fast fourier transform

Oscar Gerardo Lazo Arjona algebraicamente@gmail....
Thu Apr 29 11:17:09 CDT 2010

Hello! I'm new to this mailing list and to numpy in general.
I need to calculate fft for my optics class. But I'm having trouble.

This is the code I'm using (commented):

import pylab
import numpy as np

def g(x):
   if x>450 and x<550:
       return 1
       return 0
      f=[g(x) for x in range(0,1000)]

#this funtion can be ploted as
#which is a step function "centered" at 500

#when calculate the fft of f i get an array of complex numbers
#whose absolute value can be ploted as

#But that is not the desired output.
#Instead of that i expect something that can be ploted like this

#what i think must be happening because my function f
#has an offset of 500 (it's supposed to be centereed at 500)

#So i think it all reduces to two options:
#somehow telling fft to consider the origin at 500
#(indicate thetell the offset)

#Or make fft accept a list of points like
#so that it can know the position of the step relative to the origin

Please help!


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