From: Michael Orlitzky <michael@orlitzky.com>
Date: Fri, 12 Oct 2012 17:16:36 +0000 (-0400)
Subject: Make numbers == 3000.1.* required.
X-Git-Url: https://gitweb.michael.orlitzky.com/?a=commitdiff_plain;h=3a03a2bdc233f1504764b21149a13162486fc3bf;p=numerical-analysis.git

Make numbers == 3000.1.* required.
Import Data.Number.BigFloat in the .ghci file.
Add a doctest for newtons_method using BigFloat.
---

diff --git a/.ghci b/.ghci
index 12335d1..e5788ad 100644
--- a/.ghci
+++ b/.ghci
@@ -4,5 +4,8 @@
 -- Load everything.
 :l src/Roots/Simple.hs
 
+-- Just for convenience.
+import Data.Number.BigFloat
+
 -- Use a calmer prompt.
 :set prompt "numerical-analysis> "
diff --git a/numerical-analysis.cabal b/numerical-analysis.cabal
index 7bd0fb4..995395d 100644
--- a/numerical-analysis.cabal
+++ b/numerical-analysis.cabal
@@ -20,6 +20,8 @@ library
 
   build-depends:
     base                        == 4.5.*,
+    numbers                     == 3000.1.*,
+    -- Test deps
     HUnit                       == 1.2.*,
     QuickCheck                  == 2.*,
     test-framework              == 0.6.*,
@@ -53,6 +55,7 @@ test-suite doctests
   main-is: Doctests.hs
   build-depends:
     base      == 4.5.*,
+    numbers   == 3000.1.*,
     -- Additional test dependencies.
     doctest   == 0.7.*
 
diff --git a/src/Roots/Simple.hs b/src/Roots/Simple.hs
index 1ab9034..79750e8 100644
--- a/src/Roots/Simple.hs
+++ b/src/Roots/Simple.hs
@@ -114,6 +114,14 @@ newton_iterations f f' x0 =
 --   >>> abs (f root) < 1/100000
 --   True
 --
+--   >>> import Data.Number.BigFloat
+--   >>> let eps = 1/(10^20) :: BigFloat Prec50
+--   >>> let Just root = newtons_method f f' eps 2
+--   >>> root
+--   1.13472413840151949260544605450647284028100785303643e0
+--   >>> abs (f root) < eps
+--   True
+--
 newtons_method :: (Fractional a, Ord a)
                  => (a -> a) -- ^ The function @f@ whose root we seek
                  -> (a -> a) -- ^ The derivative of @f@