unit realroots;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  ExtCtrls, StdCtrls, Spin;

type
  Tfactorcalc = class(TForm)
    a: TSpinEdit;
    b: TSpinEdit;
    c: TSpinEdit;
    root1: TEdit;
    root2: TEdit;
    factorize: TButton;
    done: TButton;
    Label1: TLabel;
    Label2: TLabel;
    Label3: TLabel;
    Label4: TLabel;
    notice: TLabel;
    procedure doneClick(Sender: TObject);
    procedure factorizeClick(Sender: TObject);
    procedure hideme(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  factorcalc: Tfactorcalc;

implementation

{$R *.DFM}

procedure Tfactorcalc.hideme(Sender:TObject);
begin
  {vanilla code used in the onchange property of each
   spin edit to tidy up the screen inbetween trials}
  root1.Visible := false;
  root2.Visible := false;
  notice.caption := '';
end;

procedure Tfactorcalc.doneClick(Sender: TObject);
begin
  close
end;

procedure Tfactorcalc.factorizeClick(Sender: TObject);
{conditionally executes parts of the quadratic root equation thingy
depending on the value of the the thing inside the square root}

var  determinant : real;  {the thing inside the square root}

begin
     determinant := sqr(b.value) - 4*a.value*c.value;

     if determinant < 0
        then notice.caption := 'there are no real roots' 
                            {as there is no such thing as the root of a negative}

        else if determinant = 0

                then begin   
                       notice.caption := 'there is ONE real root';  
                       root1.text := floattostr(-b.value /(2*a.value));
                       root1.visible := true
                     end

                else
                     begin
                       notice.caption := 'there are TWO real roots';
                       root1.text := floattostr((-b.value+ sqrt(determinant)) /(2*a.value));
                       root2.text := floattostr((-b.value- sqrt(determinant)) /(2*a.value));
                       root1.visible := true;
                       root2.visible := true
                     end
end;

end.