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# -*- coding: utf-8 -*-
#
# Copyright (C) 2015,20016 Thorsten Liebig (Thorsten.Liebig@gmx.de)
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published
# by the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import numpy as np
def DFT_time2freq( t, val, freq, signal_type='pulse'):
assert len(t)==len(val)
assert len(freq)>0
f_val = np.zeros(len(freq))*1j
for n_f in range(len(freq)):
f_val[n_f] = np.sum( val*np.exp( -1j*2*np.pi*freq[n_f] * t ) )
if signal_type == 'pulse':
f_val *= t[1]-t[0]
elif signal_type == 'periodic':
f_val /= len(t)
else:
raise Exception('Unknown signal type: "{}"'.format(signal_type))
return 2*f_val # single-sided spectrum
def Check_Array_Equal(a,b, tol, relative=False):
a = np.array(a)
b = np.array(b)
if a.shape!=b.shape:
return False
if tol==0:
return (a==b).all()
if relative:
d = np.abs((a-b)/a)
else:
d = np.abs((a-b))
return np.max(d)<tol
if __name__=="__main__":
import pylab as plt
t = np.linspace(0,2,201)
s = np.sin(2*np.pi*2*t)
plt.plot(t,s)
f = np.linspace(0,3,101)
sf = DFT_time2freq(t, s, f, 'periodic')
plt.figure()
plt.plot(f, np.abs(sf))
plt.show()
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