How to fill end of rows of a matrix with NaN values?

I have a matrix M, and vector of indices K. I would like to make an element M(k,j) = NaN if j >= K(k). It is possible to do this with a vectorized short methode?

[Bob Thompson]

Why not just preallocate the matrix with nan values? Do you have any idea of the max size your matrix could be?

M = nan(max(k),max(j));

[Mr M.]

I think, you misunderstood my problem. Lets see an example.

let M be: [1,2,3; 1,2,3; 1,2,3; 1,2,3]; An let K be: [2; 3; 1; NaN or 4 or anithing else]. This means I need the following output:

[1;NaN,NaN; 1,2,NaN; NaN,NaN,NaN; 1,2,3]

Answer 1

[Sulaymon Eshkabilov]

Hi,

here is a simple solution, e.g.:

M = magic(5);
M(:,end)=nan

Answer 2

[Walter Roberson]

M = [1,2,3; 1,2,3; 1,2,3; 1,2,3]

M = 4×3

1 2 3 1 2 3 1 2 3 1 2 3

K = [2; 3; 1; NaN]

K = 4×1

2 3 1 NaN

M((1:size(M,2)) >= K(:)) = nan

M = 4×3

1 NaN NaN 1 2 NaN NaN NaN NaN 1 2 3