def _st(A, b, trans=0): """ solve triangular system "tril(A) @ x = b", returning x if trans==1, solve "tril(A).T @ x = b" instead. """ if b.size == 0: return b else: return _solve_triangular(A, b, trans=trans, lower=True)
def solve_triangular(L, a): return _solve_triangular(L, a, lower=True, trans='T')