矩阵的运算（相加、相乘、转置、求逆）-代码实现【C++】

矩阵的相关运算公式就不贴了，线代课本和网上都有，直接上代码。

矩阵相加：

void sum(double *const pa,double *const pb, double *const sum,const int &x,const int &y) 
{ //--------------------------------------矩阵相加
	int i,j;
	for(i=0;i<x;i++)
	{
		for(j=0;j<y;j++)
		{
			sum[i*y+j]=pa[i*y+j]+pb[i*y+j];
		}
	}
}

矩阵相乘：

void Mut(double *const pa,double *const pb, double *const Mut,const int &am,const int &an,const int &bm,const int bn) 
{ //---------------------------------------矩阵相乘
    int i,j,k,cm,cn;
    double s;
    cm = am;
    cn = bn;   
    for(i=0;i<cm;i++)
    {	 
        for (j=0;j<cn;j++)
        { 
            s=0;
            for(k=0;k<an;k++)
			{ s+=pa[i*an+k]*pb[k*bn+j];}
            Mut[i*cn+j]=s;
        }
    }       
}

矩阵转置：

void transpose(double *const A,double *const AT, const int &x,const int &y)
{
   //------------------------------矩阵转置
	int i,j;
	for(i=0;i<x;i++) 
	{
		for (j = 0; j<y; j++)
		{
			AT[j*x + i] = A[i*y + j];
		}
	}
}

矩阵求逆：

void ContraryMatrix(double *const pMatrix, double *const _pMatrix, const int &dim)
{//---------求pMatrix的逆矩阵，并存结果于矩阵_pMatrix中
    double *tMatrix = new double[2*dim*dim];
    for (int i=0; i<dim; i++){
        for (int j=0; j<dim; j++)
            tMatrix[i*dim*2+j] = pMatrix[i*dim+j];        
    }
    for (int i=0; i<dim; i++){
        for (int j=dim; j<dim*2; j++)
            tMatrix[i*dim*2+j] = 0.0;
        tMatrix[i*dim*2+dim+i]  = 1.0;        
    }
   
    for (int i=0; i<dim; i++)
    {
        double base = tMatrix[i*dim*2+i];
        
        for (int j=0; j<dim; j++)
        {
            if (j == i) continue;
            double times = tMatrix[j*dim*2+i]/base;
            for (int k=0; k<dim*2; k++)
            {        
                tMatrix[j*dim*2+k] = tMatrix[j*dim*2+k] - times*tMatrix[i*dim*2+k];
            }
        }        
        for (int k=0; k<dim*2; k++){
            tMatrix[i*dim*2+k] /= base;
        }
    }
    for (int i=0; i<dim; i++)
    {
        for (int j=0; j<dim; j++)
            _pMatrix[i*dim+j] = tMatrix[i*dim*2+j+dim];        
    }    
    delete[] tMatrix;
}