From: Michael Orlitzky Date: Wed, 19 Feb 2014 00:50:32 +0000 (-0500) Subject: Add the list_plot' function to Piecewise. X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=ba5fa4536b8171dd58afe38176da0b9c37032103;p=numerical-analysis.git Add the list_plot' function to Piecewise. --- diff --git a/src/Piecewise.hs b/src/Piecewise.hs index cf71d05..e550e4b 100644 --- a/src/Piecewise.hs +++ b/src/Piecewise.hs @@ -4,11 +4,15 @@ module Piecewise ( Piecewise(..), evaluate, evaluate', - from_intervals ) + from_intervals, + list_plot' ) where import qualified Algebra.Additive as Additive ( C ) +import qualified Algebra.Field as Field ( C ) import Control.Arrow ( first ) +import Data.Maybe ( catMaybes ) +import Misc ( partition ) import NumericPrelude import qualified Prelude as P @@ -77,3 +81,27 @@ from_intervals = where f :: (a,a) -> Predicate a f (x1,x2) x = x1 <= x && x <= x2 + + +-- | Plot a piecewise function over an interval @(x0,x1)@ using +-- 'evaluate''. Return the result a list of @(x,y)@ tuples. +-- +-- Examples: +-- +-- >>> let p1 = ((-1,0), \x -> -x) :: ((Double,Double), Double->Double) +-- >>> let p2 = ((0,1), \x -> x) :: ((Double,Double), Double->Double) +-- >>> let ivs = [p1, p2] +-- >>> let pw = from_intervals ivs +-- >>> list_plot' pw (-2) 2 4 +-- [(-2.0,0.0),(-1.0,1.0),(0.0,-0.0),(1.0,1.0),(2.0,0.0)] +-- +list_plot' :: (Additive.C a, Field.C a) + => Piecewise a + -> a + -> a + -> Int + -> [(a,a)] +list_plot' pw x0 x1 subintervals = + [ (x, evaluate' pw x) | x <- nodes ] + where + nodes = x0 : (map snd $ partition subintervals x0 x1)