将4*4矩阵的主对角线(左上-右下)及其以下的元素乘以m,输出计算以后的矩 ...答:{ int i, j, n;int a[SIZE][SIZE] = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}, {13, 14, 15, 16}};scanf("%d", &n);for (i = 0; i < SIZE; i++){ for (j = 0; j <= i; j++){ a[i][j] *= n;} } for (i = 0; i < SIZE; i...