Графики функций

__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
double x,r,a,b,c,h,y,n;
double FunS(double x,double n)
{
    double q=0,s=0;
    for(int k=0;k<=n;k++)
    {
            int f=1;
            int i=k;
            while(i>0)
            {
             f*=i;
             i--;
            }
        q=pow((-1),k)*((2*k*k+1)/f)*pow(x, 2*k);
        s+=q;
        q=0;
    }
    return s;
}
double FunY(double x)
{
 return (1-x*x/2)*cos(x)-(x/2)*sin(x);
}
void __fastcall TForm1::Button1Click(TObject *Sender)
{    //Построить график в Chart
Chart1->Series[0]->Clear();
a=StrToFloat(Edit1->Text);
b=StrToFloat(Edit2->Text);
n=StrToFloat(Edit3->Text);
h=(b-a)/n;
for (x=a;x<=b;x+=h) Chart1->Series[0]->AddXY(x,FunS(x, n));
double y0,x0,ymax,ymin,xp,yp;
y0=(Image1->Height)/2;
x0=(Image1->Width)/2;
xp=(Image1->Width)/(b-a);
ymax = ymin = FunY(b);
for (x=a;x<b;x++)
{
  double y=FunY(x);
  if (ymin>=y) ymin=y; else ymax=y;
}
yp=(Image1->Height)/(ymax-ymin);
}
void __fastcall TForm1::Button3Click(TObject *Sender)
{     //Построить график в Image
    int xmax, ymax, xt, yt, y0, x0, y_min, y_max;
    double hx, hy, x;
    Image1->Canvas->Pen->Color=clBlack;
    xmax=Image1->Width;
    ymax=Image1->Height;
    Image1->Canvas->Rectangle(0,0,xmax,ymax);
    y0=ymax/2;
    x0=xmax/2;
    Image1->Canvas->MoveTo(0,y0);
    Image1->Canvas->LineTo(xmax, y0);
    Image1->Canvas->MoveTo(x0,0);
    Image1->Canvas->LineTo(x0, ymax);
    Image1->Canvas->Pen->Color=clRed;
    Image1->Canvas->Pen->Width=2;
    hx=xmax/(b-a);
    hy=ymax/(y_max-y_min);
    Image1->Canvas->MoveTo(x0+a*hx, y0-FunY(a)*hy);
    for(x=a; x<=b; x+=h)
        Image1->Canvas->LineTo(x0+x*hx, y0-FunY(x)*hy);
}