[Commits] [svn:einsteintoolkit] IDAnalyticBH/trunk/src/ (Rev. 179)
schnetter at cct.lsu.edu
schnetter at cct.lsu.edu
Tue Mar 8 11:04:33 CST 2011
User: eschnett
Date: 2011/03/08 11:04 AM
Modified:
/trunk/src/
Kerr.c
Log:
The Kerr initial data (in
EinsteinInitialData?/IDAnalyticBH/src/Kerr.c) has a defect along the
z-axis (that is, the spin axis of the hole). The three-metric (for
instance) is not smooth across this axis, leading to discontinuities
in second spatial derivatives near there.
This appears to be due to overly crude safety measures protecting from
division by zero when calculating this data. Tweaking these measures
for more self-consistency leads to much smoother behaviour. I'm
attaching a simple patch that fixes the problem at least for
metric_type = physical.
[Patch from Bernard Kelly]
File Changes:
Directory: /trunk/src/
======================
File [modified]: Kerr.c
Delta lines: +5 -1
===================================================================
--- trunk/src/Kerr.c 2011-02-28 20:09:09 UTC (rev 178)
+++ trunk/src/Kerr.c 2011-03-08 17:04:33 UTC (rev 179)
@@ -117,8 +117,12 @@
/* Define coordinate functions */
xx=x[i]; yy=y[i]; zz=z[i];
rho_2=xx*xx+yy*yy;
- if (rho_2<epsilon) rho_2=epsilon;
rho=sqrt(rho_2);
+ if (rho<epsilon) {
+ xx=epsilon;
+ rho_2=xx*xx+yy*yy;
+ rho=sqrt(rho_2);
+ }
R_2=rho_2+zz*zz;
R=sqrt(R_2);
R_3=R*R_2;
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