function convolve

Convolve an image with a kernel. The resulting array is returned with bitpix -32.

result = convolve(a, b)

a:   The array to be convolved.
b:   The kernel to convolve the image with.

If a and b are of exactly the same size, the two are multiplied in fourier space. If b is smaller than a and a square matrix, a convolved with the kernel b is returned.