[Commits] [svn:einsteintoolkit] Multipole/trunk/src/ (Rev. 103)

[ian.hinder at aei.mpg.de]

User: hinder
Date: 2013/10/09 12:57 PM

Modified:
 /trunk/src/
  integrate.cc

Log:
 integrate.cc: Add a comment on the lack of symmetry of the "midpoint" integration method

File Changes:

Directory: /trunk/src/
======================

File [modified]: integrate.cc
Delta lines: +7 -0
===================================================================
--- trunk/src/integrate.cc	2013-10-09 17:57:15 UTC (rev 102)
+++ trunk/src/integrate.cc	2013-10-09 17:57:23 UTC (rev 103)
@@ -41,6 +41,13 @@
 
   assert(nx > 0); assert(ny > 0); assert (f);
 
+  // This sum should probably exclude the upper end points.  As
+  // currently implemented, it does not naturally map to the "sum of
+  // areas" definition of the integral, as there is an additional
+  // contribution from the last term in the sum.  This introduces an
+  // additional first order error to a method which is already only
+  // first order.
+
   for (iy = 0; iy <= ny; iy++)
     for (ix = 0; ix <= nx; ix++)
       integrand_sum += f[idx(ix,iy)];