When performing indexing, there is a difference between a logical array and a double array containing only 0 and 1. The former works and performs logical indexing, the latter does not work and throws an error because there's no such thing as element 0, row 0, column 0, page 0, etc. of an array in MATLAB.
x = 1:10
L = mod(x, 2) == 0
D = double(L)
onlyEvens1 = x(L) % Works
onlyEvens2 = x(D) % Errors
If mask is a double array containing just 0's and 1's you'll need to convert it into a logical array to use it for indexing. The easiest way to do this is to call the logical function on it.
L2 = logical(D)
isequal(L, L2) % True
onlyEvens3 = x(L2)
