;;; PLT Scheme Science Collection
;;; random-distributions/gaussian-tail-graphics.ss
;;; Copyright (c) 2004 M. Douglas Williams
;;; This library 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 2.1 of the License, or (at your option) any later version.
;;; This library is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; Lesser General Public License for more details.
;;; You should have received a copy of the GNU Lesser General Public
;;; License along with this library; if not, write to the Free
;;; Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
;;; 02111-1307 USA.
;;; -------------------------------------------------------------------
;;; This code implements graphics for Gaussian tail distributions.
;;; Version  Date      Description
;;; 0.1.0    08/07/04  This is the initial release of the Guassian tail
;;;                    distribution graphics routines. (Doug Williams)
;;; 1.0.0    09/28/04  Added contracts for functions.  Marked as ready
;;;                    for Release 1.0.  (Doug Williams)

(module gaussian-tail-graphics mzscheme
  (require (lib "contract.ss"))
    (-> real? real? (>=/c 0.0) any))
    (-> real? any)))
  (require "gaussian-tail.ss")
  (require (lib "plot.ss" "plot"))
  ;; gaussian-tail-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-tail-plot a mu sigma)
    (plot (line (lambda (x) (gaussian-tail-pdf x a mu sigma))
                     (color 'red))
          (x-min a)
          (x-max (+ a (* 3 sigma)))
          (x-label "x")
          (y-min 0) (y-max 1)
          (y-label "Density")
          (title "Gaussian Tail Distribution")))
  ;; unit-gaussian-tail-plot: -> void
  ;; Plot the pdf and cdf for a unit gaussian distribution (standard
  ;; normal distribution).  The x axis range is +/- three.
  (define (unit-gaussian-tail-plot a)
    (plot (line (lambda (x) (unit-gaussian-tail-pdf x a)) (color 'red))
          (x-min a) (x-max (+ a 3))
          (x-label "x")
          (y-min 0) (y-max 1)
          (y-label "Density")
          (title "Unit Gaussian Tail Distribution")))