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。-Matrix class. This class includes matrix, int rows, and the ranks of the number of variables int cols, matrix data array double data [][], constructor Matrix (), Matrix (int rows, int cols), Matrix (int rows, int cols, double data [] []), to obtain the value of an element methods getData (int row, int col), set the value of an element methods setData (int row, int col, double value), the calculation method of the product of two matrices multiply (Matrix m) as well as the toString () and so on.