MATLAB: Vectorization of 3 nested for loops.

improving speedMATLABnested for loopsvectorization

I have 3 for loop and I want to vectorized it .
I try a lot to do it but I cannot do it.
This is the simple version.
I can't explain the whole situation but:
A is 100*82.
B is 203*2000.
C is 1*10.
D is 100*5*2000.
for nset=1:100
    for nindy=1:5
        for nimp=1:2000
if A(nset,2+(nindy-1).*3)==1
    if B(33.*6+nindy,nimp)<= C(1+(nindy-1).*2)+...
        ((C(2+(nindy-1).*2)-C(1+(nindy-1).*2))./11).*A(nset,1+(nindy-1).*3)
         D(nset,nindy,nimp)=1;
      end
  end
         end
      end
  end
I want to replace the 3 for loops with vectorization…
Thanks….

Best Answer

I don't think that your code can be vectorized. However, this should be a bit faster
for nset=1:100
    for nindy=1:5
        if A(nset,2+(nindy-1).*3)==1
            C17 = C(1+(nindy-1).*2)        ...
                + ((C(2+(nindy-1).*2)-C(1+(nindy-1).*2))./11).*A(nset,1+(nindy-1).*3);
            for nimp=1:2000
                if B(33.*6+nindy,nimp) <= C17
                    D(nset,nindy,nimp) = 1;
                end
            end
        end
    end
end
Caveat: I have neither tested correctness nor speed.
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