operaciones con matrices aplicación Java

prefacio

Matlab en unos simples operaciones de la matriz, quiere darse cuenta de sus propias palabras que gastar un montón de esfuerzo.
principio de funcionamiento de la matriz no es explicar, se olvide amigos puede volver atrás mirando a través de los libros.

código

public class MatrixCalculate {
    //矩阵加法 C=A+B
    public static double[][] MatrixAdd(double[][] m1,double[][] m2){
        if(m1!=null||m2!=null||
           m1.length!=m2.length||
           m1[0].length!=m2[0].length) {
            return null;
        }

        double[][] m = new double[m1.length][m1[0].length];

        for(int i=0;i<m.length;++i){
            for (int j=0;j<m[i].length;++j){
                m[i][j]=m1[i][j]+m2[i][j];
            }
        }

        return m;
    }

    //矩阵转置
    public static double[][] MatrixTranspose(double[][] m){
        if (m==null) return null;
        double[][] mt=new double[m[0].length][m.length];
        for(int i=0;i<m.length;++i){
            for (int j=0;j<m[i].length;++j){
                mt[j][i]=m[i][j];
            }
        }
        return mt;
    }

    //矩阵相乘 C=A*B
    public static double[][] MatrixMultiply(double[][] m1,double[][] m2){
        if(m1==null||m2==null||m1[0].length!=m2.length)
            return null;

        double[][] m=new double[m1.length][m2[0].length];
        for(int i=0;i<m1.length;++i){
            for(int j=0;j<m2[0].length;++j){
                for (int k=0;k<m1[i].length;++k){
                    m[i][j]+=m1[i][k]*m2[k][j];
                }
            }
        }
        
        return m;
    }

    //求矩阵行列式（需为方阵）
    public static double MatrixDet(double[][] m){
        if (m==null||m.length!=m[0].length)
            return 0;

        if (m.length==1)
            return m[0][0];
        else if (m.length==2)
            return Matrix2Det(m);
        else if (m.length==3)
            return Matrix3Det(m);
        else {
            int re=0;
            for (int i=0;i<m.length;++i){
               re+=(((i+1)%2)*2-1)*MatrixDet(CompanionMatrix(m,i,0))*m[i][0];
            }
            return re;
        }
    }

    //求二阶行列式
    public static double Matrix2Det(double[][] m){
        if (m==null||m.length!=2||m[0].length!=2)
            return 0;

        return m[0][0]*m[1][1]-m[1][0]*m[0][1];
    }

    //求三阶行列式
    public static double Matrix3Det(double[][] m){
        if (m==null||m.length!=3||m[0].length!=3)
            return 0;

        double re=0;
        for (int i=0;i<3;++i){
            int temp1=1;
            for(int j=0,k=i;j<3;++j,++k){
                temp1*=m[j][k%3];
            }
            re+=temp1;
            temp1=1;
            for(int j=0,k=i;j<3;++j,--k){
                if (k<0) k+=3;
                temp1*=m[j][k];
            }
            re-=temp1;
        }

        return re;
    }

    //求矩阵的逆（需方阵）
    public static double[][] MatrixInv(double[][] m){
        if (m==null||m.length!=m[0].length)
            return null;

        double A=MatrixDet(m);
        double[][] mi=new double[m.length][m[0].length];
        for(int i=0;i<m.length;++i){
            for (int j=0;j<m[i].length;++j){
                double[][] temp=CompanionMatrix(m,i,j);
                mi[j][i]=(((i+j+1)%2)*2-1)*MatrixDet(temp)/A;
            }
        }

        return mi;
    }

    //求方阵代数余子式
    public static double[][] CompanionMatrix(double[][] m,int x,int y){
        if (m==null||m.length<=x||m[0].length<=y||
            m.length==1||m[0].length==1)
            return null;

        double[][] cm=new double[m.length-1][m[0].length-1];

        int dx=0;
        for(int i=0;i<m.length;++i){
            if(i!=x){
                int dy=0;
                for (int j=0;j<m[i].length;++j){
                    if (j!=y){
                        cm[dx][dy++]=m[i][j];
                    }
                }
                ++dx;
            }
        }
        return cm;
    }
}