If I understand you correctly, you should rewrite your function as:
function Output = perspective_projection(Input)
Output = bsxfun(@rdivide, Input(:,1:2), Input(:,3));
end
or, judging from the way you seem to be calling it:
function [OutputX,OutputY] = perspective_projection(Input)
OutputX = Input(:,1)./Input(:,3);
OutputY = Input(:,2)./Input(:,3);
end
Note that your function is quite simple (I wouldn't even use a function):
[X,Y] = deal(Input(:,1)./Input(:,3), Input(:,2)./Input(:,3));
As for your original function: the error is in the initialization:
function Output = perspective_projection(Input)
%// WRONG: this initializes a 3D array!
Output = zeros(size(Input));
%// ...but you want a 2D array
for ii = 1: length(Input)
Output(ii,1) = Input(ii,1)/Input(ii,3);
Output(ii,2) = Input(ii,2)/Input(ii,3);
end
end
and of course, the multiple outputs (but it's not quite clear to me whether you want that or not...)