Question

*** Write a function called reverse_diag that creates a square matrix whose elements are 0
except for 1s on the reverse diagonal from top right to bottom left. The reverse diagonal of an nby-
n matrix consists of the elements at the following indexes: (1, n), (2, n-1), (3, n-2), … (n, 1). The
function takes one positive integer input argument named n, which is the size of the matrix, and
returns the matrix itself as an output argument. Note that using the built-in functions eye and
diag are not allowed. (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. Note that the grader will not test for n = 1,
but try to solve it for that case too.)

Answer 1

reverse_diag.m

function M = reverse_diag(n)
M = zeros(n);
M(sub2ind(size(M),size(M,1):-1:1,1:size(M,2))) = 1;