График функции Y=A*EXP(X)

//---------------------------------------------------------------------------
 
#include <vcl.h>
#pragma hdrstop
#include<math.h>
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::BitBtn1Click(TObject *Sender)
{
float y,a,x,i;
if ((e1->Text.Length()==0)||(e2->Text.Length()==0))
 MessageDlg("Не все поля заполнены! ",mtWarning,TMsgDlgButtons()<<mbOK,0);
else
{
 a=StrToFloat(e1->Text);
 i=StrToFloat(e2->Text);
 Series1->Clear();
 x=0;
 while (x<=i)
 {
  y=a*exp(x);
  Series1->AddXY(x,y);
  x+=0.1;
 }
}
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::e1KeyPress(TObject *Sender, char &Key)
{
TEdit *e1;
e1=(TEdit*)Sender;
if ((Key>='0')&&(Key<='9'))
  return;
switch(Key)
{
case VK_BACK:  return;
case VK_RETURN: return;
}
Key=0;
}
//---------------------------------------------------------------------------

if(i>700)
{
ShowMessage("Error i>700");
return;
}