Hi Andreas and others, I want to run a function on a large, 2D complex array (eventually 2*12x2*12 datapoints). However, pycuda does not work as expected. The ElementWise function doesn't work at 2d arrays, so I used the SourceModule function with block sizes. The problem is now that the C code on the GPU does not give the same result as the numpy calculation on the CPU. Very large and strange numbers are resulting. I also made a post on http://stackoverflow.com/q/13031439/1768422, because the source code is easier to read. What's going wrong in my code? Kind regards, Vasco