Interpolyacsia obschego vida. POG

#include <iostream.h>
#include <iomanip.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

int i,j,k, m;
double P, Y[101], G[101][101], B[101], xT[101], yT[101], D[101];

void main(void)
{
//Sostavlenie matricsi G
//---------------------------------------|
    const a=4;
    const b=7;
    const m=4;
    const n=4;
    double x[101];
    for (i=0; i<m; i++)
    {
        x[i]=a+i*(b-a)/(m-1);
    }
    for (i=0; i<m; i++)
    {
        for (j=0; j<m; j++)
        {
            G[i][j]=pow(x[i],j);
        }
    }
    for (i=a; i<=b; i++)
    {
        B[i-4]=exp(i)/pow(i,3)-pow(sin(i),3);
    }
//---MG----------------------------------|
    int size=m;
    double koeff, koeff2, C[101];
    for (i=0; i<size; i++)
    {
        for (j=i; j<size-1; j++)
        {
            koeff=G[j+1][i]/G[i][i];
            B[j+1]-=B[i]*koeff;
            for (k=i; k<size; k++)
            {
                G[j+1][k]-=G[i][k]*koeff;
            }
        }
    }
    for (i=size-1; i>=0; i--)
    {
        for (j=i-1; j>=0; j--)
        {
            koeff2=G[j][i]/G[i][i];
            B[j]-=B[i]*koeff2;
        }
    }
    for (i=size-1; i>0; i--)
    {
        for (int j=i-1; j>=0; j--)
        {
            G[j][i]=0;
        }
    }
    for (i=0; i<size; i++)
    {
        C[i]=B[i]/G[i][i];
    }
//---POG---------------------------------|
    for (i=0; i<31; i++)
    {
        xT[i]=a+i*(b-(double)a)/30;
    }
    int q=0;
    double t;
    for (t=4; t<=7; t=t+0.1)
    {
        yT[q]=exp(t)/pow(t,3)-pow(sin(t),3);
        q++;
    }
    for (i=0; i<31; i++)
    {
            P=C[n-2]+xT[i]*C[n-1];
            for (k=3; k<=n; k++)
            {
                P=C[n-k]+xT[i]*P;
            }
            Y[i]=P;
    }
    for (i=0; i<31; i++)
    {
        D[i]=fabs(yT[i]-Y[i]);
    }
//---Vivod-tablicsi-rezyltatov-----------|
    cout<<"F(x) = e^x / x^3 - (sin(x))^3"<<"   na intervalle  ["<<a<<","<<b<<"]"<<endl;
    cout<<"_____________________________________________________________"<<endl;
    cout<<"No#:     X:        Y:            Y.approx       Pogreshnost':"<<endl;
    cout<<"_____________________________________________________________"<<endl;
    for (i=0; i<31; i++)
    {
        printf("#%2d ---- %3.2f ---- %7.6f ---- %8.7f ---- %7.10f\n",i+1,xT[i],yT[i],Y[i],D[i]);
    }
    getch();
}