unit TwoZProbUnit;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
  StdCtrls, ExtCtrls;

type

  { TTwozProbForm }

  TTwozProbForm = class(TForm)
    Bevel1: TBevel;
    CancelBtn: TButton;
    Panel1: TPanel;
    ResetBtn: TButton;
    ComputeBtn: TButton;
    ReturnBtn: TButton;
    ProbEdit: TEdit;
    Label3: TLabel;
    Z2Edit: TEdit;
    Label2: TLabel;
    Z1Edit: TEdit;
    Label1: TLabel;
    procedure ComputeBtnClick(Sender: TObject);
    procedure FormActivate(Sender: TObject);
    procedure ResetBtnClick(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end; 

var
  TwozProbForm: TTwozProbForm;

implementation

{$R *.lfm}

uses
  Math, MathUnit, Utils;

{ TTwozProbForm }

procedure TTwozProbForm.ResetBtnClick(Sender: TObject);
begin
  ProbEdit.Text := '';
  Z1Edit.Text := '';
  Z2Edit.Text := '';
end;

procedure TTwozProbForm.ComputeBtnClick(Sender: TObject);
var
  z1, z2, prob : double;
begin
  if not MyTryStrToFloat(Z1Edit.Text, z1) then
  begin
    Z1Edit.SetFocus;
    ErrorMsg('No valid number.');
    exit;
  end;

  if not MyTryStrToFloat(Z2Edit.Text, z2) then
  begin
    Z2Edit.SetFocus;
    ErrorMsg('No valid number.');
    exit;
  end;

  prob := abs(NormalDist(z2) - NormalDist(z1));
  ProbEdit.Text := Format('%6.4f', [prob]);
end;

procedure TTwozProbForm.FormActivate(Sender: TObject);
var
  w: Integer;
begin
  w := MaxValue([CancelBtn.Width, ResetBtn.Width, ComputeBtn.Width, ReturnBtn.Width]);
  CancelBtn.Constraints.MinWidth := w;
  ResetBtn.Constraints.MinWidth := w;
  ComputeBtn.Constraints.MinWidth := w;
  ReturnBtn.Constraints.MinWidth := w;
end;

end.