该程序功能是使数组左下半三角元素的值会全部置成0。其中左下半三角元素的下标特点是列下标小于或等于行下标。-The program function is to enable all left the lower triangle of the array element values will be reset to 0.Lower triangular elements of the left subscr ipt subscr ipt is characterized by columns is less than or equal to the row index.