Command Reference : Matrix Language Reference
Syntax: @vech(o)
Argument: matrix, sym, o
Return: vector
Creates a vector from the columns of the lower triangle of the source square matrix o stacked on top of each another. The vector has the same number of elements as the source matrix has in its lower triangle. Example:
sym s1 = @mrnd(5,5)
vector v1 = @vech(m1)
creates a sym matrix S1 and stacks its lower triangle in a 15 element vector V1.
See also @unvech.