Excuse me, I'm a beginner in C++
I want to calculate physics system so that I need to use large variable.

Code:
double multiply_matrix_RP(int u0,int u1,int u2,int u3,int u4,int u5,int u6,int u7,int u8)
{
        //u0,u1~u8 there are material array
	long double _Rp[9];
	for(int i=0;i<=8;i++)
       {
	_Rp[i]=EAI[i][0]*u0+EAI[i][1]*u1+EAI[i][2]*u2+EAI[i][3]*u3+EAI[i][4]*u4+EAI[i][5]*u5+EAI[i][6]*u6+EAI[i][7]*u7+EAI[i][8]*u8;	
	}
	return _Rp[9];
}

void CImp_simDlg::OnOK() 
{
	// TODO: Add extra validation here
	double _Rp[9];
	_Rp[9]=multiply_matrix_RP(Rp[0],Rp[1],Rp[2],Rp[3],Rp[4],Rp[5],Rp[6],Rp[7],Rp[8]);

	//CDialog::OnOK();
}
But it actually have error message when it compiler.
Please help me to solve, thank every much!!!