将矩阵A进行PLU分解，把矩阵Ａ的上三角部分存放Ｕ的元素并覆盖Ａ，把Ａ的严格下三角部分存放Ｌ的严格下三角元素并覆盖A-A matrix PLU decomposition, the upper triangular matrix A of the U element and the A, the A of the strict lower triangular part of the L A