this is a forward substitution solver for non-singular upper triangular matrices . b = u-1b where b is a vector , u is an n by n matrix . concode_field_sep PlaceHolder placeHolder concode_field_sep void solveL concode_elem_sep void solveL concode_elem_sep void invertLower concode_elem_sep void invertLower concode_elem_sep void solveTranL