Problem 42634. Minimum of each diagonal

The well-known min function can operate along either the rows or the columns of a matrix by using

[Y,I] = min(X,[],1) or [Y,I] = min(X,[],2)

but it cannot operate along a diagonal dimension. For this problem, create a function that returns the smallest component along each diagonal of a matrix (starting with the one-element diagonal in the bottom left corner of the matrix).

Example

If

X = magic(3) = [8 1 6
                3 5 7
                4 9 2]

then

Y = mindiag(X) = [4 3 2 1 6]

See also maxdiag.