Make specific columns of a matrix zero.

Hi Mathworks community!

So I have a matrix A such as:

A = [1,2,3,4,5,6,7,8,9; 5,8,6,44,8,6,8,7,3; 9,8,7,6,5,4,3,2,1]

And an array b that specifies the columns I' DON´T want to make zero:

b = [1,4,5,9]

Getting an output such as:

out = [1,0,0,4,5,0,0,0,9; 5,0,0,44,8,0,0,0,3; 9,0,0,6,5,0,0,0,1]

I'm working with much bigger dimensions so, Any ideas of how to do this efficiently?

Thank you!

Santos

Answer 1

[Stephen23]

A = [1,2,3,4,5,6,7,8,9; 5,8,6,44,8,6,8,7,3; 9,8,7,6,5,4,3,2,1];
b = [1,4,5,9];
out = zeros(size(A));
out(:,b) = A(:,b)

out = 3×9

1 0 0 4 5 0 0 0 9 5 0 0 44 8 0 0 0 3 9 0 0 6 5 0 0 0 1

[Santos García Rosado]

Thank you Stephen! Exactly what I was looking for.