From: Michael Orlitzky <michael@orlitzky.com>
Date: Tue, 15 Apr 2014 14:50:14 +0000 (-0400)
Subject: Fix a bug in the relative error.
X-Git-Url: http://gitweb.michael.orlitzky.com/?p=numerical-analysis.git;a=commitdiff_plain;h=be30f3a5a4c10d4a3c9eb42e38e2ce3306d42c85;hp=45aa63a662556bc9ed0f6018f9f3f580586f38a9

Fix a bug in the relative error.
---

diff --git a/src/FEM/R1.hs b/src/FEM/R1.hs
index 28317a6..9ce8387 100644
--- a/src/FEM/R1.hs
+++ b/src/FEM/R1.hs
@@ -615,8 +615,7 @@ relative_error_pointwise :: forall m n l a.
                          -> a -- ^ The point @x@ at which to compute the error.
                          -> a
 relative_error_pointwise pde params u x =
-  cent * ( u_exact - u_fem ) / u_exact
+  cent * ( abs $ (u x) - u_fem ) / ( abs $ u x )
   where
-    u_exact = abs $ u x
     u_fem = evaluate' (solution pde params) x
     cent = fromInteger 100