import Numeric
import FFT
import Gnuplot

L = 128
U = 1./8
UL = int(L*U)

gp = Gnuplot.Gnuplot()
gp.title = ('FFT Demo')
gp('set xrange [0:%s]' % L)

X = range(L)
f = Numeric.array([1.0]*UL+[0.0]*(L-UL))
### folding
#f = Numeric.array([1.0]*(UL/2)+[0.0]*(L-UL+1)+[1.0]*(UL/2-1))
### non-sharp cutoff
S = [2./UL*i for i in range(UL/2)]
SR = S[:]
SR.reverse()
#f = Numeric.array([1.0]*(UL/4)+SR+[0.0]*(L-UL-UL/2+1)+S+[1.0]*(UL/4-1))
d = Gnuplot.Data(X,f, with='lines lw 2', title='Original Function')
gp.plot(d)

raw_input('Press Return')

F = FFT.fft(f)
Fr = Gnuplot.Data(X,F.real, with='lines lw 2', title='FFT Real part')
Fi = Gnuplot.Data(X,F.imag, with='lines lw 2', title='FFT Imaginary part')
gp.plot(Fr,Fi)

raw_input('Press Return')