diff --git a/interp/tools.py b/interp/tools.py
index f0b354f..eceb168 100644
--- a/interp/tools.py
+++ b/interp/tools.py
@@ -49,7 +49,7 @@ def friendly_exact_3D(X):
   x,y,z = X
   return 1 + x*x + y*y + z*z
 
-def improved_answer(answer, exact, verbose=False):
+def improved_answer(answer, exact):
   if not answer['error']:
     return True
 
@@ -64,3 +64,7 @@ def improved_answer(answer, exact, verbose=False):
   else:
     log.debug(":( damaged result")
     return False
+
+
+def percent_improvement(answer, exact):
+  return np.abs(answer['qlin'] - exact) / exact