Нахождение производной методом центральных разностей

#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
#include <iostream.h>
#include <math.h>
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//double x=[100];
//double y=[100];
//double z(double x);
double y(double x)
{
  return sin(x);
}
double a;
double b;
double n;
double h;
void dif(double a, double b, double n, double h)
{
h=(a+b)/n;
//b=x[n];
//double delta_x=(x[i+1]-x[i-1]);
 
double s[1000];
 
//double delta_y=(y(x+2*h)-y(x-2*h));
double dif_y=(y(x+2*h)-y(x-2*h))/(2*h);
for (int i=1; i<n-1;i++)
s[i]=dif_y(x);
}
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Memo1->Clear();
double a;
double b;
double n;
a=StrToFloat(Edit1->Text);
b=StrToFloat(Edit2->Text);
n=StrToFloat(Edit3->Text);
dif(a,b,n,h);
double s[1000];
for (int i=1; i<n-1;i++)
if (s[i])
Memo1->Lines->Add(FloatToStr(s[i])+"  ");
 
}
//---------------------------------------------------------------------------