int size = some_number; 
A = new double *[size+1];
for(int i=1;i<=size; i++){
A[i] = new double [size+1]; 
}

int Nsteps, Npos;

double dz;

// arrays to hold the field values
double *x_old;
double *x_new;

class class_name{
public:
   class_name(); // Constructor

// Member functions
   void function_1();
   void function_2(double *mat);
   void function_3();

   void function_2_re_def(double *mat);
   void function_3_re_def();

public:
   int rows;
   int cols;

   double *v1;

void read_data(char *file,int &ndata,double *x,double *y)
{
	//Read the data from the file and store it in memory
	//This reads the data stored in the two column file and stores it in memory

char *overlapfile;

overlapfile=(char *)(f1.c_str());

int file;
errno_t err=_sopen_s(&file,overlapfile,_O_BINARY,_SH_DENYNO,_S_IREAD);

if(file==-1){
    perror("Failed to open file");
}
else{
    //Import data
}

const char *

string drive="c:\\"
string dir1="Output_Files\\";
string dir2="Calculation_Data\\";

pos=(int)(strcspn(buf,","));

posa=(int)(strcspn(buf,","));
posb=(int)(strcspn(buf,"\n"));
pos=Min(posa,posb); // Min is a template function that returns the minimum of posa and posb

ifstream data;
data.open(file,ios_base::in);

int buf_size=1024*1024*10;
char *BUF=new(char[buf_size]);

//header file

class froot{
public:
	void calculate_root(int i);
	double F(double x);
	double G(double x);
	
	double find_root(double (*g)(double),double x1,double x2,int &depth);
	double root(double x1,double x2,double (*g)(double),double f1,double f2,int &depth);

private:

#define PI 3.1415926535897932385

#define PI 4.0*atan(1.0)