[Rivet] mcplots

[Peter Skands]

Hi Hendrik,

Thanks for the tips, I hope we can implement most of them!

> I've looked at this for a while, and since the problem still exists, I
> thought I'd better mention it. What is the technical problem you
> experience? Maybe we can help you solving it?

Yes, our problem is in batching Rivet :) So far, the message I got from Andy was 
that if we came up with a solution he'd be happy to implement it, provided it 
was the solution he wanted :) Our production system is up and running, but we 
are not able to combine the outputs of several runs yet. That's essentially the 
limiting factor, since we need to keep the running time of each job 
"reasonable". For us, this also affects producing histograms with Alpgen, for 
instance, where we need to merge the output of several runs. We are close, 
though, but the solution we have so far is not fully general. (Save event 
numbers and cross sections for each generator run and combine assuming errors in 
quadrature, which will only be correct for a subset of distributions, but among 
them are some of the important ones that really need higher stats so I was 
content to do this as a first step.) I understood that some work in this 
direction has also gone on inside Rivet, but that a general solution is also 
there at least a few releases away?

Cheers,
Peter