[ET Trac] [Einstein Toolkit] #1195: Modify bisection algorithm in EOS_Omni's nuc_eos

Einstein Toolkit trac-noreply at einsteintoolkit.org
Tue Dec 11 08:57:21 CST 2012

#1195: Modify bisection algorithm in EOS_Omni's nuc_eos
  Reporter:  eschnett               |       Owner:        
      Type:  enhancement            |      Status:  review
  Priority:  major                  |   Milestone:        
 Component:  EinsteinToolkit thorn  |     Version:        
Resolution:                         |    Keywords:        

Comment (by eschnett):

 Christian Ott tells me that he is currently re-designing part of this
 algorithm anyway. We should therefore wait before modifying the code.

 Ian: Yes, the reason is that the temperature is more evenly distributed in
 log T than in T.

 This routine is a generic EOS table lookup routine, and doesn't know
 anything about past timelevels or neighbouring points. This routine
 already uses log T for many operations. It only goes to great lengths to
 switch back to T, apply the bisection step, and then switch back to log T.
 My argument is that this additional complication is not necessary, and
 likely even slows down convergence.

 Frank: This routine is not a generic bisection routine. It is supposed to
 find the temperature corresponding to a particular internal energy, since
 the EOS table is provided in terms of log T, while the code passes in the
 internal energy.

 I did not add calls to log, I removed them. If you go to
 then the green lines are added, not the red ones.

Ticket URL: <https://trac.einsteintoolkit.org/ticket/1195#comment:4>
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