Question

I need to implement the following algorithm in Matlab.

1. Suppose A = [3 4 1 9 5]
2. permute A randomly say, A = [5 1 4 3 9]
3. Add 2 to the first two elements: A = [7 3 4 3 9]
4. permute A back, A = [3 4 3 9 7]

I am using randperm() function to permute:

index = randperm(numel(A));
A = A(index);

But the problem is how to permute it back, after changing array A to the first permutation.

Answer 1

You can actually put the indexing on the left hand side:

A(index) = A;

😉