Write a function called identity that creates a square identity matrix, which is a matrix whose elements are 0 except for the elements on the diagonal (from top left to bottom right) which have a value of 1. The diagonal consists of those elements whose row and column indexes are the same: (1,1), (2,2), etc. The function takes one positive integer input argument, which is the size of the matrix, and returns the matrix itself as an output argument. For example, identity(4) must return a 4-­‐by-­‐4 identity matrix. You are not allowed to use the built-­‐in eye or diag functions. (Hint: you can index into a matrix with a single index and MATLAB will handle it as if it was a vector using column-­‐major order.)

function M = identity(n)
M = zeros(n);
M(1:n+1:end)=1;