for looop convert to arrayfun

I want to convert these for loops into an arrayfun. Always give me an error

"All of the input arguments must be of the same size and shape.

Previous inputs had size 31 in dimension 1. Input #5 has size 1"

[X,Y,Z] = sph2cart(ThetaRad,PhiRad,1.0); 
nElec = length(M.lab);                   
EF(nElec,nElec) = 0;                     

for i = 1:nElec; 
    for j = 1:nElec;                     
        
     EF(i,j) = 1 - ( ( (X(i) - X(j))^2 + ...
     (Y(i) - Y(j))^2 + (Z(i) - Z(j))^2 ) / 2 );
    end; 
end;

I tried to create a new funciton:

function EF = gpuefg(X,Y,Z, maxiter)

    EF(maxiter,maxiter) = 0;

for i = 1:maxiter; 
    for j = 1:maxiter;       

        EF(i,j) = 1 - ( ( (X(i) - X(j))^2 + ...
        (Y(i) - Y(j))^2 + (Z(i) - Z(j))^2 ) / 2 );
end; 
    end;
    
end

And call it

EFG = gpuArray(EF);


.
.
.

EFG = arrayfun(@gpuefg,X,Y,Z, nElec, 'UniformOutput', false );

But not working, how should I do this?

[David Hill]

Please explain what you are trying to do. What are your inputs and expected outputs?

[Question Mr]

Here is my original code: (not the whole is just the point)

[X,Y,Z] = sph2cart(ThetaRad,PhiRad,1.0); 
nElec = length(M.lab);                   
EF(nElec,nElec) = 0;                     

for i = 1:nElec; 
    for j = 1:nElec;                     
        
     EF(i,j) = 1 - ( ( (X(i) - X(j))^2 + ...
     (Y(i) - Y(j))^2 + (Z(i) - Z(j))^2 ) / 2 );
    end; 
end;

output is a matrix

And I tried to create my own function for change two "for" loop

function EF = gpuefg(X,Y,Z, maxiter)
        EF(maxiter,maxiter) = 0;

for i = 1:maxiter; 
    for j = 1:maxiter;       
        EF(i,j) = 1 - ( ( (X(i) - X(j))^2 + ...
        (Y(i) - Y(j))^2 + (Z(i) - Z(j))^2 ) / 2 );
end; 
    end;
    
end

Output is matrix like in the original "EF(i,j)" (well that is the plan)

When I called:

EFG = gpuArray(EF);
...

EFG = arrayfun(@gpuefg,X,Y,Z, nElec, 'UniformOutput', false );

It's crashed but I dont know why,

EFG is a gpuArray,

X,Y,Z my function's inputs

nElec is my function's maxiter

So the point is, I want to swap these two "for loops" for one "arryfun"

Answer 1

[Matt J]

The way to do this with arrayfun, (which I don't think will be optimal here) would be,

[I,J]=ndgrid(gpuArray(1:nElec));

fun=@(i,j) 1 - ( ( (X(i) - X(j))^2 +  (Y(i) - Y(j))^2 + (Z(i) - Z(j))^2 ) / 2 );

EF= arrayfun(fun,I,J);

[Question Mr]

Thank you

[Matt J]

You are welcome, but please Accept-click one of the answers (I expect the first one) to indicate that it resolved your problem.

[Question Mr]

I have another question. I tried you solution but I got this error:

"Use of functional workspace is not supported.

For more information see Tips."

What should I do now? I've wroten the code into the .m file

[Matt J]

Why did you Accept the answer if it didn't work? Why not just go with the other answer, which I told you should be better than arrayfun?

Answer 2

[Matt J]

The more efficient way to do what you are attempting is with the 2 lines of code,

X=X(:);  Y=Y(:); Z=Z(:);

EF = 1 - ( (X-X.').^2 + (Y-Y.').^2 + (Z-Z.').^2)/2 ;