MemoryError in python

[ttbluemoon0220]

When I tried to calculate two-dimensional FFT of the array with 4096*4096 elements by using 64bit Windows XP with 64GB,
I ran into the Memoryerror althogh the usage of memory was less than 1GB.

I am wondering whether python has the upper limit memory usage.
Even if so, I don't know how to set the upper limit memory usage.

I showed you my code as follows.

Could you help me, please ?

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#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
if __name__ == '__main__':
    pass
 
import scipy 
import scipy.io
import scipy.fftpack
import scipy.stats
import pylab 
import random
import os
import math
import cmath
 
h=   2.46342852e-03  # rms of height
size_mesh = 1.0 
l=   85.16152053/math.sqrt(2.0)*80.0/512/size_mesh 
N=    512
L=    512 
 
F = scipy.zeros((N,N),dtype=scipy.complex128 )
 
 
for I in scipy.arange(0,N-1,1):
    for J in scipy.arange(0,N-1,1):
        Kx=2.0*math.pi*I/L
        Ky=2.0*math.pi*J/L
        if (I == 0) or (I == N/2) or (J == 0) or (J == N/2):
            rdm_number= random.gauss(0,1)
        else:
            rdm_number= (random.gauss(0,1) +1.0j*random.gauss(0,1) )/math.sqrt(2.0)
        F[I,J]=2.0*math.pi*L*math.sqrt(l**2*h**2/(4.0*math.pi)*scipy.exp(-Kx**2*l**2/4.0 -Ky**2*l**2/4.0))*rdm_number
 
for I in scipy.arange(1,N/2-1,1):
    for J in scipy.arange(1,N/2-1,1):
        F[N-I,N-J]= F[I,J].conjugate()
 
for I in scipy.arange(N/2+1,N-1,1):
    for J in scipy.arange(1,N/2-1,1):
        F[N-I,N-J]= F[I,J].conjugate()
 
RS = scipy.fftpack.ifft2(F)
 
del F
 
scipy.io.write_array(
    os.path.join("RS.txt"), 
        RS, 
        separator=" " 
    )
 
pylab.clf()
Z = scipy.real(RS) 
 
del RS
 
pylab.imshow(Z)
pylab.contour(Z)
pylab.xlabel('x')
pylab.ylabel('y')
pylab.savefig( os.path.join("RS.png"))
pylab.clf()
 
del  Z
 

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