(self)
return all(self[i, j].is_zero
            for i in range(self.rows)
            for j in range(i + 1, self.cols))
Check if matrix is a lower triangular matrix. True can be returned
        even if the matrix is not square.

        Examples
        ========

        >>> from sympy import Matrix
        >>> m = Matrix(2, 2, [1, 0, 0, 1])
        >>> m
        Matrix([
        [1, 0],
        [0, 1]])
        >>> m.is_lower
        True

        >>> m = Matrix(4, 3, [0, 0, 0, 2, 0, 0, 1, 4 , 0, 6, 6, 5])
        >>> m
        Matrix([
        [0, 0, 0],
        [2, 0, 0],
        [1, 4, 0],
        [6, 6, 5]])
        >>> m.is_lower
        True

        >>> from sympy.abc import x, y
        >>> m = Matrix(2, 2, [x**2 + y, y**2 + x, 0, x + y])
        >>> m
        Matrix([
        [x**2 + y, x + y**2],
        [       0,    x + y]])
        >>> m.is_lower
        False

        See Also
        ========

        is_upper
        is_diagonal
        is_lower_hessenberg
Check if matrix is a lower triangular matrix. True can be returned
        even if the matrix is not square.
Check if matrix is a lower triangular matrix . True can be returned even if the matrix is not square .
def is_lower(self):
        """Check if matrix is a lower triangular matrix. True can be returned
        even if the matrix is not square.

        Examples
        ========

        >>> from sympy import Matrix
        >>> m = Matrix(2, 2, [1, 0, 0, 1])
        >>> m
        Matrix([
        [1, 0],
        [0, 1]])
        >>> m.is_lower
        True

        >>> m = Matrix(4, 3, [0, 0, 0, 2, 0, 0, 1, 4 , 0, 6, 6, 5])
        >>> m
        Matrix([
        [0, 0, 0],
        [2, 0, 0],
        [1, 4, 0],
        [6, 6, 5]])
        >>> m.is_lower
        True

        >>> from sympy.abc import x, y
        >>> m = Matrix(2, 2, [x**2 + y, y**2 + x, 0, x + y])
        >>> m
        Matrix([
        [x**2 + y, x + y**2],
        [       0,    x + y]])
        >>> m.is_lower
        False

        See Also
        ========

        is_upper
        is_diagonal
        is_lower_hessenberg
        """
        return all(self[i, j].is_zero
            for i in range(self.rows)
            for j in range(i + 1, self.cols))
def is_lower ( self ) : return all ( self [ i , j ] . is_zero for i in range ( self . rows ) for j in range ( i + 1 , self . cols ) )