program in c++ for fft, python equivalent, using gsl library

I have this code in python(that use numpy):

def convolve(z,n=21,std=3):
kernel = windows.gaussian(2 * n - 1,std)
y_pad = pad(z,(n,n),'edge')
f = fft.rfft(y_pad)
w = fft.rfft(kernel,y_pad.shape[-1])
y = fft.irfft(w * f)

I would have the c++ code equivalent usin gsl library.
the results obtained must be the same