unit tProbUnit;

{$mode objfpc}{$H+}

interface

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

type

  { TTProbForm }

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

var
  TProbForm: TTProbForm;

implementation

{$R *.lfm}

uses
  Math, MathUnit, Utils;

{ TTProbForm }

procedure TTProbForm.ResetBtnClick(Sender: TObject);
begin
  tValueEdit.Text := '';
  DFEdit.Text := '';
  ProbEdit.Text := '';
end;

procedure TTProbForm.ComputeBtnClick(Sender: TObject);
var
  tvalue, prob: double;
  dfValue: Integer;
begin
  if not MyTryStrToFloat(tValueEdit.Text, tvalue) then
  begin
    tValueEdit.SetFocus;
    ErrorMsg('No valid number.');
    exit;
  end;

  if not TryStrToInt(DFEdit.Text, dfValue) then
  begin
    dfEdit.SetFocus;
    ErrorMsg('Not a valid integer (must be positive).');
    exit;
  end;

  if tvalue >= 0.0 then
    prob := 0.5 * ProbT(tvalue, dfvalue)
  else if tvalue < 0.0 then
    prob :=  1.0 - ProbT(tvalue, dfvalue) + (0.5 *ProbT(tvalue, dfvalue))
  else
    prob := 0.50;

  ProbEdit.Text := Format('%6.4f', [prob]);
end;

procedure TTProbForm.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.