[Rivet] alpgen+herwig in agile 1.2.2

[Gavin Hesketh]

Hello,
Although I'm a bit worried I might be gaining a reputation as an alpgen 
defender, there is a bug in the new agile which means alpgen+herwig will 
not run correctly.

There are two small tweaks, calling:
 > FC_HWEVNT.IERROR = -1;
and
 > continue; (instead of return)
when UPVETO fails.

Calling IERROR ensures the event count is correct at the end of the run 
(mostly cosmetic, unless people use this to normalise). Calling continue 
ensures agile does not spit out empty events if upveto fails (which can 
be very often) - this is more serious, and basically makes it unusable 
as (eg) rivet aborts on seeing an empty event.

The two patched files are attached, the diff is below.

cheers,
Gavin





 > diff AlpGenFHerwigJimmy.cc 
build/AGILe-1.2.2/src/AlpGen/AlpGenFHerwigJimmy.cc
70d70
<         FC_HWEVNT.IERROR = -1;
72c72
<           continue;
---
 >           return;








 > diff AlpGenFHerwig.cc build/AGILe-1.2.2/src/AlpGen/AlpGenFHerwig.cc
57,70c57,65
<
<     while (true) {
<       FC_HWUINE();  // Initialize event
<       FC_HWEPRO();  // Generate hard subprocess
<       // Call the matching routine
<       int imatch = 0;
<       FC_UPVETO(&imatch);
<       if (imatch != 0) {
<       MSG_DEBUG("Event killed by UPVETO");
<       FC_HWEVNT.IERROR = -1;
<       FC_HWUFNE();
<       continue;
<       }
<       break;
---
 >     FC_HWUINE();  // Initialize event
 >     FC_HWEPRO();  // Generate hard subprocess
 >     // Call the matching routine
 >     int imatch = 0;
 >     FC_UPVETO(&imatch);
 >     if (imatch != 0) {
 >       MSG_DEBUG("Event killed by UPVETO");
 >       FC_HWUFNE();
 >       return;
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