#lang racket
;;; Science Collection
;;; random-distributions/gamma-graphics.rkt
;;; Copyright (c) 2004-2011 M. Douglas Williams
;;;
;;; This file is part of the Science Collection.
;;;
;;; The Science Collection is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation, either version 3 of the License
;;; or (at your option) any later version.
;;;
;;; The Science Collection is distributed in the hope that it will be useful,
;;; but WITHOUT WARRANTY; without even the implied warranty of MERCHANTABILITY
;;; or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
;;; License for more details.
;;;
;;; You should have received a copy of the GNU Lesser General Public License
;;; along with the Science Collection.  If not, see
;;; <http://www.gnu.org/licenses/>.
;;;
;;; -------------------------------------------------------------------
;;;
;;; This code implements graphics for gaussian distributions.
;;;
;;; Version  Date      Description
;;; 0.1.0    09/17/04  This is the initial release of the gamma
;;;                    distribution graphics routines. (Doug Williams)
;;; 1.0.0    09/28/04  Added contracts for functions.  Marked as ready
;;;                    for Release 1.0.  (Doug Williams)
;;; 1.1.0    02/09/06  Added cdf.  (Doug Williams)
;;; 2.0.0    11/19/07  Changed calls to unchecked versions.
;;;                    (Doug Williams)
;;; 3.0.0    06/09/08  Changes required for V4.0.  (Doug Williams)
;;; 3.0.1    07/01/08  Changed x axis label.  (Doug Williams)
;;; 4.0.0    08/16/11  Changed the header and restructured the code. (MDW)

(require "gamma.ss"
         plot)

;;; gamma-plot: real x real -> 2d-view%
(define (gamma-plot a b)
  (plot (mix (line (lambda (x) (unchecked-gamma-pdf x a b))
                   #:color 'red)
             (line (lambda (x) (unchecked-gamma-cdf x a b))
                   #:color 'blue))
        #:x-min 0.001 #:x-max 24.0
        #:x-label "X"
        #:y-min 0 #:y-max 1
        #:y-label "Density"
        #:title "Gamma Distribution"))

;;; Module Contracts

(provide/contract
 (gamma-plot
  (-> (>/c 0.0) real? any)))