[Commits] [svn:einsteintoolkit] Multipole/trunk/ (Rev. 68)

[ian.hinder at aei.mpg.de]

User: hinder
Date: 2010/11/15 02:42 PM

Modified:
 /trunk/
  param.ccl

Log:
 Change default interpolator parameters to disable off-centering of stencil
 
 AEILocalInterp by default will off-centre the interpolation stencil if
 there are insufficient points to perform the interpolation.  In a
 parallel setting, this could happen due to there being insufficient
 ghost points for the interpolator chosen.  The off-centering leads to
 an interpolation error which is of the correct order but larger than
 for a centered stencil.  More importantly, it leads to different
 results on different numbers of processes.  With this commit,
 Multipole will (by default) disable off-centering in the interpolator.

File Changes:

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

File [modified]: param.ccl
Delta lines: +7 -1
===================================================================
--- trunk/param.ccl	2010-11-04 16:42:55 UTC (rev 67)
+++ trunk/param.ccl	2010-11-15 20:42:48 UTC (rev 68)
@@ -10,8 +10,14 @@
 CCTK_STRING interpolator_pars "Parameters for the interpolator"
 {
     ".*" :: "Any string that Util_TableSetFromString() will take"
-} "order=3"
+} "order=3 boundary_off_centering_tolerance={0.0 0.0 0.0 0.0 0.0 0.0} boundary_extrapolation_tolerance={0.0 0.0 0.0 0.0 0.0 0.0}"
 
+# The above makes sure that the interpolator doesn't off-centre the
+# interpolation stencil if there are insufficient points to
+# interpolate, which can happen if there are insufficient ghost-zones
+# for the interpolation method used, and can lead to processor-number
+# dependent results.
+
 CCTK_STRING coord_system "What is the coord system?"
 {
     ".*" :: "Any smart string will do"