NAME
    mattrace - trace of a square matrix

SYNOPSIS
    mattrace(m)

TYPES
    m		square matrix with summable diagonal elements

    return	determined by addition of elements

DESCRIPTION
    For a two-dimensional square matrix, mattrace(m) returns the sum of
    the elements on the principal diagonal.  In particular, if m
    has been created by mat m[N,N] where N > 0, mattrace(m) returns

		m[0,0] + m{1,1] + ... + m[N-1,N-1]

EXAMPLE
    > mat m[2,2] = {1,2,3,4}
    > print mattrace(m), mattrace(m^2)
    5 29

LIMITS
    none

LIBRARY
    none

SEE ALSO
    mat, mattrans