[Halld-offline] Minutes, GlueX Offline Software Meeting, Apr. 6, 2011

[Mark M. Ito]

Find the minutes at 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_Offline_Meeting%2C_April_6%2C_2011#Minutes 
and as text below.

==

GlueX Offline Meeting, April 6, 2011
Minutes

Present:
* CMU: Curtis Meyer
* IU: Ryan Mitchell, Kei Moriya, Matt Shepherd
* JLab: Hovanes Egiyan, Mark Ito (chair), Yi Qiang, Simon Taylor,
Elliott Wolin
* UR: Andrei Semenov, Irina Semenova


Announcements

Mark reminded us of the new [34]release of sim-recon that came out this
week.

Matt remarked that some of the data in the calibration database can
change the behavior of the code in a given release and that we should
consider tagging a set of calibration constants along with the code.
Since we do not have a calibration database yet that supports freezing
of the constants we need some alternate mechanism for doing it.

Mark thought that in the cases where numbers need to be frozen, more
than likely they should be parameters in the source code, using the
configuration scheme that David described at an earlier meeting. Then
default values are captured along with the standard release tag.

Matt mentioned that CLEO had similar parameters in a database along
with calibration constants and so both were captured with the single
tag.

We agreed that in the current situation we have no other choice but to
tag the calibrations in some way using subversion. Mark agreed to come
up with a scheme.

Review of minutes from the last meeting

We reviewed the [36]minutes of the March 23 meeting.

We discussed Matt's feature request: that builds not depend on
previously installed versions of themselves, include files in
particular. David pointed out that when individual programs are checked
out, they must depend on previous installed versions of include files
from the libraries tree. Any implementation of the feature will have to
take this into account.

Checking sort comparison algorithms

David has gone through our code and found all instances of provision of
a custom sort function sorting STL vectors. There were only two
instances where a floating calculation is involved in the comparison.
These will be/have been changed to use pre-calculated member data. This
addresses the problem found with optimized code that has SIMD
instructions disabled. See [38]his slides for details.

χ^2's of tracking

Kei has done a study of the χ^2 values returned from the tracking code,
using the particle gun, for a wide range of momenta and polar angles.
He finds that the the resulting distributions have departures from the
ideal distribution; in terms of χ^2 probability, there are peaks at
both high and low probability. The effect varies depending on angle and
momentum. He has started reading through the code to find the origin of
the numbers so that he can carry his study further. See [[40]slides]
for details.

Action Item Review

We went through [42]the list.

We agreed that "resolved" should mean that the problem was resolved and
work on it has stopped. "Closed" should mean work on it has stopped,
but the problem was not resolved.

New Action Items

1. Propose scheme for tagging calibration constants. -> Mark
2. Look into using "externals" in subversion to coordinate different
packages. -> Mark


Review of recent repository activity

We went through [45]the list.

Simon found that his code was getting the pointer to geometry and
B-field for every event. He noticed that fixing this sped things up by
about 20%.

Retrieved from 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_Offline_Meeting%2C_April_6%2C_2011

References

34. https://mailman.jlab.org/pipermail/halld-offline/2011-April/000626.html
36. 
http://www.jlab.org/Hall-D/software/wiki/index.php/GlueX_Offline_Meeting%2C_March_23%2C_2011#Minutes
38. 
http://www.jlab.org/Hall-D/software/wiki/images/f/f9/20110406_sort_algorithms.pdf
40. https://halldweb1.jlab.org/talks/2011-2Q/chi2talk.pdf|his
42. 
https://halldweb1.jlab.org/mantisbt/search.php?project_id=1&sticky_issues=on&sortby=last_updated&dir=DESC&highlight_changed=336&hide_status_id=-2
45. 
http://clasweb.jlab.org/websvn/prod/log.php?repname=GlueX&path=%2Ftrunk%2Fsim-recon%2F&rev=0&sc=0&isdir=1