Метод деления отрезка пополам по С++

//---------------------------------------------------------------------------
 
#include <vcl.h>
#include <math.h>
#pragma hdrstop
 
#include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
: TForm(Owner)
{
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button1Click(TObject *Sender)
{
float a,b,e,z,f,x;
if(((Edit1->Text).Length()==0)||((Edit2->Text).Length()==0))
{
MessageDlg("Необходимо ввести значение",mtInformation,TMsgDlgButt ons()<< mbOK,0);
if ((Edit1->Text).Length()==0)
Edit1->SetFocus();
else
Edit2->SetFocus();
return;
}
a=StrToFloat(Edit1->Text);
b=StrToFloat(Edit2->Text);
e=StrToFloat(Edit3->Text);
try
{
x=(a+b)/2;
return pow(x,4)+(0.5*pow(x,3))-(4*pow(x,2))-(3*x)- 0.5;
if (x>e)
b=x;
else a=x;
x=(a+b)/2;
}
catch (EZeroDivide &e)
{
ShowMessage("");
Edit2->SetFocus();
return x;
}
Label4->Caption="Результат= : "+ FloatToStrF(f,ffGeneral,7,2); }
//-------------------------------------------------
 
void __fastcall TForm1::Edit1KeyPress(TObject *Sender, char &Key)
{
if((Key >='0')&&(Key<='9'))
return;
//---------------------------------------------------------------------------
if(Key == DecimalSeparator)
{
if ((Edit1->Text).Pos(DecimalSeparator) !=0)
Key = 0;
return;
}
if(Key == VK_BACK)
return;
if (Key == VK_RETURN)
{
Edit2->SetFocus();
return;
}
}
 
void __fastcall TForm1::Edit2KeyDown(TObject *Sender, WORD &Key,
TShiftState Shift)
{
if ((Key >= '0')&&(Key <='9')) return;
//---------------------------------------------------------------------------
if(Key == DecimalSeparator) {
if((Edit2->Text).Pos(DecimalSeparator) !=0)
Key=0;
return;
}
if(Key == VK_BACK)
return;
if (Key==VK_RETURN)
{
Button1->SetFocus();
return;
}
Key=0;
}
void __fastcall TForm1::Button2Click(TObject *Sender)
{
Form1->Close();
}
//---------------------------------------------------------------------------
 
 
void __fastcall TForm1::EditChange(TObject *Sender)
{
Label4->Caption ="";
}
//---------------------------------------------------------------------------
 
void __fastcall TForm1::Button3Click(TObject *Sender)
{
Label4->Caption="";
Edit1->Text="";
//---------------------------------------------------------------------------
Edit2->Text="";
}