Subject: AI26.10 function to calculate fractional exposure


  Dear all,

  following up on AI 26.10, I've given some thought to a common
function to calculate fractional exposures based on GTIs. The
original intention was to have this in DAL3JEMX, but currently
I would rather lean to the creation of a j_tools_lib component
(following the SPI team example) that would be under our own 
control and have less overhead in updating. This component could 
then also include jemx.h. But back to the problem at hand ...

  I propose two have two functions, based on some utility
functions I already have, but somewhat extended:

JEMXgetGTI(group,
           instrument,                       [JMX1 or JMX2]
           gtiNamesUsed,                     [usually "MERGED"]
           *numGTI,
           **gtiStartOBT,
           **gtiEndOBT,
           **gtiStartIJD,
           **gtiEndIJD,
           chatter,status)

  would take an ISDC group (SWG, OG or Index of SWG)
  loop over all ScWs in there, allocate buffers of
  sufficient size and fill them with GTI information in 
  OBT and IJD. numGTI tells you how many there are in total.


JEMXgoodFraction(numIntervals,*intervalStart,*intervalEnd,
                 numGTI,*gtiStartIJD,*gtiEndIJD,
                 **goodFraction,
                 chatter,status)

   would loop over a list of time intervals in IJD, and calculate
   for each the fraction (0.0-1.0 covered by the given GTIs).


Are these interfaces what you would like to have? 
Should I work on starting a j_tools_lib component including them?
What other functions could be included in that component?

  regards,
  Peter