[d2n-analysis-talk] BB TDC cuts

[MATTHEW R POSIK]

On Wed, May 26, 2010 at 11:05 AM, Brad Sawatzky <brads at jlab.org> wrote:

> On Wed, 26 May 2010, MATTHEW R POSIK wrote:
>
> > On Wed, May 26, 2010 at 10:15 AM, Brad Sawatzky <brads at jlab.org> wrote:
> >
> > > On Sat, 22 May 2010, posik at jlab.org wrote:
> > >
> > > > So I think I finally got the BB cer multihit TDCs working right. I
> > > > just use TString cuts for all hits in the TDC. For example the
> > > > beam line side has 6 hits, so I do something like
> > > >
> > > > TString tdc1_1 =
> > > >
> "DL.BBcerT01[Ndata.DL.BBcerT01-1]>xx&&DL.BBcerT01[Ndata.DL.BBcerT01-1]<xx"
> > >
> > > What happens when Ndata.DL.BBcerTxx==0?  Will it attempt to index with
> > > '-1' or do you watch for that condition prior to invoking this cut?
> >
> > Yes, I took this condition in to account by appending the condition
> > Ndata.DLBBcerTxx!=0 to all 20 TDCs.
>
> You should not just add Ndata.DLBBcerTxx!=0 to the end of the Cut
> string.  The software must still evaluate all of the bogus [-1] indexes.
> If those memory locations are out of scope, then you can segfault or
> throw some other error.  Same problem if you try to invoke a cut for
> "hit 6" when there are less than 6 hits -- in either case you're
> indexing beyond the scope of the array.  That kind of code is just
> begging for trouble :-)
>
> [ . . . ]
> > Following the suggestion of this site
> >
> http://root.cern.ch/phpBB3//viewtopic.php?p=34643&sid=0337d028a3147d554b6b650c9474eddd
> > I was able to fix that problem. I think this cut is now correctly
> working.
>
> It looks like the default limit is 1000.  Are you really intending to
> generating a cut with more than 1000 comparisons?  How big do you have
> to set it?
>

Right now I have it set to 10000. I have five comparisons for 1 hit on TDC1:

  1) for Ndata !=0
  2) && with the TDC hit cut windows
  3) Hit one less than a TDC channel
  4) Hit one greater than a TDC channel
  5) another && between the two high and low TDC channels

This is then done for 20 TDCs. This gives 5*20 = 600 comparisons.
I then make another cut called "TString tdc_1 = OR of all the one hits in
the 20 TDCs"  this is another 19 comparisons, which now total 600+19=619
comparisons
This is then done for 6 hits, so the comparisons are now 619*6 = 3714
comparisons.

Is there a more efficient way to do this? I only did it this way because it
was the most straight forward.

-matt



>
> -- Brad
>
> --
> Brad Sawatzky, PhD <brads at jlab.org>  -<>-  Jefferson Lab / Hall C / C111
> Ph: 757-269-5947  -<>-  Fax: 757-269-5235  -<>- Pager: brads-page at jlab.org
> The most exciting phrase to hear in science, the one that heralds new
>  discoveries, is not "Eureka!" but "That's funny..."   -- Isaac Asimov
>



-- 
Matthew Posik
Email: posik at temple.edu
Temple University Physics Dept.
Office: BA-319
Office #:  215-204-1331
WebSites:
Temple:
http://quarks.temple.edu/
d2n:
http://hallaweb.jlab.org/experiment/E06-014/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://mailman.jlab.org/pipermail/d2n-analysis-talk/attachments/20100526/7aacf36b/attachment-0001.html