#lang racket/gui
;;; Science Collection
;;; random-distributions/gaussian-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    08/07/04  This is the initial release of the Guassian
;;;                    distribution graphics routines. (Doug Williams)
;;; 1.0.0    09/28/04  Added contracts for functions.  Marked as ready
;;;                    for Release 1.0.  (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)
;;; 4.1.0    10/09/11  Updated to new plot package. (MDW)

(require plot

;;; gaussian-plot: real x real -> void
;;; Plot the pdf and cdf for a gaussian distribution with the given
;;; mean and standard deviation.  The x axis range is +/- three sigma
;;; around the mean.
(define (gaussian-plot mu sigma)
  (plot (list (function (lambda (x) (gaussian-pdf x mu sigma))
                        #:label "y = pdf(x)"
                        #:color "red")
              (function (lambda (x) (gaussian-cdf x mu sigma))
                        #:label "y = cdf(x)"
                        #:color "blue"))
        #:x-min (+ mu (* -3 sigma))
        #:x-max (+ mu (* 3 sigma))
        #:x-label "x"
        #:y-label "Density"
        #:title "Gaussian Distribution"))

;;; unit-gaussian-plot: -> void
;;; Plot the pdf and cdf for a unit gaussian distribution (standard
;;; normal distribution).  The x axis range is +/- three.
(define (unit-gaussian-plot)
  (plot (list (function unchecked-unit-gaussian-pdf
                        #:label "y = pdf(x)"
                        #:color "red")
              (function unchecked-unit-gaussian-cdf
                        #:label "y = cdf(x)"
                        #:color "blue"))
        #:x-min -3 #:x-max 3 #:x-label "x"
        #:y-label "Density"
        #:title "Unit Gaussian Distribution"))

;;; Module Contracts

  (-> real? (>=/c 0.0) (or/c (is-a?/c image-snip%) void?)))
  (-> (or/c (is-a?/c image-snip%) void?))))