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MATLAB利用parfor計算多重for迴圈

 當MATLAB程式中出現多個for迴圈時,為提高執行效率,可用如下方式實現迴圈變數索引。

clear; clc;

M = 2;
N = 3;
R = 4;

parfor i = 1 : M * N * R
    ii = floor((i - 1) / (N * R)) + 1;
    jj = floor(mod(i - 1, N * R) / R) + 1;
    kk = mod(i - 1, R) + 1;
	fprintf('i = %d j = %d k = %d\n', ii, jj, kk);
end

執行結果

i = 1 j = 3 k = 4
i = 1 j = 3 k = 3
i = 1 j = 3 k = 2
i = 1 j = 3 k = 1
i = 1 j = 2 k = 4
i = 1 j = 2 k = 3
i = 1 j = 2 k = 2
i = 1 j = 2 k = 1
i = 1 j = 1 k = 4
i = 1 j = 1 k = 3
i = 1 j = 1 k = 2
i = 1 j = 1 k = 1
i = 2 j = 1 k = 4
i = 2 j = 1 k = 3
i = 2 j = 1 k = 2
i = 2 j = 1 k = 1
i = 2 j = 3 k = 1
i = 2 j = 2 k = 4
i = 2 j = 2 k = 3
i = 2 j = 2 k = 2
i = 2 j = 2 k = 1
i = 2 j = 3 k = 2
i = 2 j = 3 k = 3
i = 2 j = 3 k = 4