# Re-arrange matrix based on index on GPU using arrayfun

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Tutu on 12 Jul 2019
Commented: Tutu on 2 Aug 2019
Hi,
I want to re-arrange a two dimensions frequency domain x,y to p=sqrt(x^2+y^2) on GPU. I can do so with the code below. However, it it is pretty slow for my application (2 seconds). I have read about arrayfun but could not make it work for my purpose. Any help is much appreciated.
nx=200;
Nx=floor(nx/2);
ny=100;
Ny=floor(ny/2);
t=200;
Nt=floor(t/2);
A=gpuArray(single(rand(nx,ny,t)));
A=fft2(A);
A=A(1:Ny,1:Nx,:);
freqx=0:1/nx:1/2-(1/nx);
freqy=0:1/ny:1/2-(1/ny);
A=fft(A,nz,3);
G=gpuArray(single(zeros(Ny*Nx,Nt+1)));
for ii=1:Nx
for jj=1:Ny
G((ii-1)*ny+jj,1)=sqrt(freqx(1,ii)^2+freqy(1,jj)^2);
G((ii-1)*ny+jj,2:end)=abs(squeeze(A(jj,ii,1:Nt)));
end
end
Ma=max(G(:,1));
bin=Ma/100;
Y=gpuArray(single(zeros(100,Nt+1)));
for ii=1:100
loik= (G(:,1)>=(bin*(ii-1)) & G(:,1)<(bin*(ii)));
Y(ii,:)=mean(G(loik,:));
end
Any help is appreciated.
Thanks
Tutu on 2 Aug 2019

R2019a

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