//矩阵相乘
public double[][] multiplyMatrix(double[][] a,double[][] b){
if(a[0].length != b.length) {
return null;
}
double[][] c=new double[a.length][b[0].length];
for(int i=0;i<a.length;i++) {
for(int j=0;j<b[0].length;j++) {
for(int k=0;k<a[0].length;k++) {
c[i][j] += a[i][k] * b[k][j];
}
}
}
return c;
}
//矩阵相减
public double[][] MatrixSubt(double[][]A,double[][] B){
if (A.length != B.length || A[0].length != B[0].length )
{
return (null);
}
double[][]C=new double[A.length][A[0].length];
for(int i=0;i<A.length;i++)
{
for(int j=0;j<A[0].length;j++)
{
C[i][j]=A[i][j]-B[i][j];
}