Программа вывода графиков функции Y(x)

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
 
#include "Unit1.h"
#include "math.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::Button3Click(TObject *Sender)
{
double x,y,k;
int a=2;
int b=3;
x=StrToFloat(Edit1->Text);
k=StrToFloat(Edit2->Text);
Series1->Clear();
for(x;x<=k;x=x+0.1)
{y=(2*a*x+b*cos(sqrt(abs(x))))/(pow(x,2)+5);
Series1->AddXY(x,y);}
Chart1->Refresh();
  Chart1->LeftAxis->Increment=(Chart1->LeftAxis->Maximum-Chart1->LeftAxis->Minimum)/5;
}
 
//---------------------------------------------------------------------------
void __fastcall TForm1::Button1Click(TObject *Sender)
{
Image1->Picture->Bitmap->Width = Image1->Width;
Image1->Picture->Bitmap->Height = Image1->Height;
 
double x_min = 0;
double dx = 2 * M_PI * 15;
int a=2;
int b=3;
double y_min = 0;
double dy = 4;
 
double x = x_min;
double y =(2*a*x+b*cos(sqrt(abs(x))))/(pow(x,2)+5);
int _y = Image1->Picture->Bitmap->Height - (y - y_min) / dy * Image1->Picture->Bitmap->Height;
Image1->Picture->Bitmap->Canvas->MoveTo(0, _y);
 
for (int i = 0; i < Image1->Picture->Bitmap->Width; i++)
{
    double x = x_min + dx * i / Image1->Picture->Bitmap->Width;
    double y = (2*a*x+b*cos(sqrt(abs(x))))/(pow(x,2)+5);
    int _y = Image1->Picture->Bitmap->Height - (y - y_min) / dy * Image1->Picture->Bitmap->Height;
    Image1->Picture->Bitmap->Canvas->LineTo(i, _y);
}
}
//---------------------------------------------------------------------------

double length = end - start;  // start и end твои данные из  эдитов
for (int x = 0; x < length; x = x+step)  // заданный шаг
{
   double y = x*2; // тут уравнение
   Series1->Add(x, y); 
}

  double y = start*2; // уравнение
Image1->Picture->Bitmap->Canvas->MoveTo(start,y);
for (int x = start; x < end; x = x+step) 
{
   y = x*2; // уравнение
   Image1->Picture->Bitmap->Canvas->LineTo(x,y);
}