（1）　　设计和编写代表矩阵的Matrix类。该类包括矩阵行列数变量int rows和int cols，矩阵数据数组double data[][]，构造方法Matrix()、Matrix(int rows,int cols)、Matrix(int rows,int cols,double data[][])，获取某元素值的方法getData(int row,int col)，设置某元素值的方法setData(int row,int col,double value)，计算两个矩阵的乘积的方法multiply(Matrix m)以及toString()等内容。-(1) design matrix and write on behalf of the Matrix class. This category includes the number of variables int rows matrix ranks and int cols, matrix array of data double data [][], constructor Matrix (), Matrix (int rows, int cols), Matrix (int rows, int cols, double data [] []) method to obtain the value of an element getData (int row, int col), set the value of an element of the method setData (int row, int col, double value), the calculation of two matrices method multiply (Matrix m) and toString () and so on.