I've seen a function in numpy (http://docs.scipy.org/doc/numpy/reference/generated/numpy.gradient.html) for calculating the gradient of a 2-dimensional array. Numpy also provides 2 examples on that website (I'm more interested in the second one).
I now want to use such a function in C++. Does anyone know if there is such a function in GSL? Or can someone explain to me what the numpy function does, so that I can write my own in C++?
Thanks for any help.