substituting value in matrix does not work for some reason

A = [6 9 NaN NaN 8 NaN]; B = [2 5 342 232 1 116];

sizeA = size(A);

for m = [1:1:size(2)];

    if A(1,m) == NaN;
       B(1,m) = NaN;
    end;
end;

I was hoping B would become [2 5 NaN NaN 8 NaN], but it did not change. I would appreciate any help

Answer 1

[Kelly Kearney]

You can't use == with NaNs:

>> NaN == NaN

ans =

       0

Use isnan instead:

B(isnan(A)) = NaN;

Answer 2

[Kevin Claytor]

Logical indexing makes this much easier;

B(A==NaN) = NaN;