MATLAB: How to count numer of “1” in matrix

matrix operations

i have i matrix with 1/0 (binary img) and i want to count all "1" that are in that matrix. how can i do that??

The easiest way:

nr_ones = nnz(matrix);

You could consider using find() or strfind() or sum() or nnz() or == or ismember() or length() or numels()

nnz(v == a)

You will probably also see

sum(v == a)

The nnz() version works for multidimensional arrays as well, whereas the sum() version would count along the first non-scalar dimension.