MATLAB: Numerical integration with the GPU? Trapz appears to be unsupported in arrayfun, are there any alternatives

Question

I’ve recently discovered GPU computing in Matlab and it’s been helping me a lot with speeding up slow calculations, so I want to implement it wherever I can now. I have been sending things to the GPU by creating a function file of what I want to calculate and then calling it with arrayfun. But I can’t figure out how to send this slow formula to the GPU:

for minute=1:1440
     for beta = 1:181 
q=trapz(TotalTilted(minute,beta,:));
Amp(minute,beta,:)=TotalTilted(minute,beta,:)*IntegratedRadiation(minute,beta)/q; 
     end
end

Whatever I have been trying so far it’s been telling me: “argument contains unsupported or unknown function 'trapz'”

Like the GPU doesn’t support trapz, but according to the documentation I’ve seen trapz should be possible on the GPU: http://www.mathworks.com/help/distcomp/run-built-in-functions-on-a-gpu.html

However, from what I can see trapz is not listed under supported functions for arrayfun which I suspect could be the problem. Is there a different way to do numerical integration with arrayfun? Or does anyone know how I could go about calculating this formula on the GPU with a different approach other than arrayfun?

Answer 1

In this case, I think you can simply use the vectorized version of trapz, and then apply arrayfun to expand IntegratedRadiation and q in the third dimension:

q = trapz(TotalTilted, 3);
Amp = arrayfun(@(a, b, c) a * b / c, TotalTilted, IntegratedRadiation, q);