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<div dir="ltr">Dear Alexander, Thanks for the information.  It looks like doable. it is also convenient to use LHAPDF library to re-calcualte the pdf value for each event, given the P_Z of two partons, and Q value.  I didn't pay enough attention to those information,which are already printed in each event line. Regards, Yong <div class="gmail_quote">On Wed, Jul 23, 2008 at 12:51 PM, Alexander Sherstnev <<a href="mailto:cherstn@hep.phy.cam.ac.uk">cherstn@hep.phy.cam.ac.uk</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Dear Yong, x1 and x2 can be easily calculated from current data in event files. P_Z components of the initial particles are the 1st and 2nd column in the file. pdf values are available in sqme.c The file is generated automatically by s_comphep.exe and located in results: Here is the peace of code:  if(!strfun_calc)  { strfun_calc=1;    q=qcd_Scale_chep();    if(ans0) xstr0=strfun_(0,xbjo[0],xbjo[1],q);    if(ans1) xstr1=strfun_(1,xbjo[0],xbjo[1],q);  } In fact strfun_ returns pdf1*pdf2, since CompHEP has got an implemented approach with  non-factorized PDF (we call it hash-model). If you use the standard pdf: strfun_(1,xbjo[0],xbjo[1],q) = 0 strfun_(0,xbjo[0],xbjo[1],q) = pdf (xbjo[0], q) * pdf (xbjo[1], q) If you need you can add the number to the old format file in src/num/evnt_format1.c, the routine write_event_frmt1(...) It is quite easy to get how to modify it. With best regards, -- Dr. Alexander Sherstnev, Cavenidish Laboratory, University of Cambridge, and SINP, Moscow State University <a href="http://www.hep.phy.cam.ac.uk/people/sherstnev.html" target="_blank">http://www.hep.phy.cam.ac.uk/people/sherstnev.html</a> </blockquote></div> </div>