vectorized_lower_tri_to_mat function

Turns symmetric 2D array into a lower triangular matrix

vectorized_lower_tri_to_mat(v, dim)

Arguments

• v: A list of length (dim * (dim + 1) / 2).
• dim: The number of rows (equivalently, columns) in the output array.

Returns

Return the symmetric 2D array defined by taking "v" to specify its lower triangular matrix.