what happens if store the indexes of one matrix into other?

I had data matrix "kdata" which is 4 D with the size of 512*100*20*11. If I sort another data matrix "Y" and store its indexes in the second dimension of the data matrix what happens? I am using following code

for ii=1:nt                              
    tmp1=kdata(:,:,:,ii);
    [~,index]=sort(y(:,ii),'descend');
    tmp1=tmp1(:,index,:);
end

[Stephen23]

" If I sort another data matrix "Y" and store its indexes in the second dimension of the data matrix..."

You are not "storing" the indices at all, but using them to rearrange the order of the second dimension of tmp1.

"...what happens?"

Try it and find out.

[Iram Shahzadi]

Thank you @Stephen Cobeldick. I got it