Pyxplot

Download this example: script.ppl output.eps output.png

Using Pyxplot's Fourier transform command

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Script

set numerics complex
step(x) = tophat(x,0.5)
fft [-1:1:0.01] f() of step()
set key outside
plot [-10:10] Re(f(x*1)) title texify("Re(f(x))"), sinc(pi*x)