16 How to access some MC parameters

During MC running, sometimes you need to access MC parameters and plot them. To do this, you should copy them in the array REAL rUSER(50) (from ``getevkin.inc''). This should be done in the main loop of the FORTRAN program.

For example, for PYTHIA6, copy necessary variables to the rUSER array in ``main/mcarlo/pythia-62/RUNMC-pythia6.f'' after the line ``nev=nev+1''. Then you can access this variable in any of your function (like ``user_afill.cpp'' under ``proj'') if you specify the include file `` #include<getevkin.h>'' and put the line ``extern getevkincommon getevkin_ ;'', You variable should be seen as ``getevkin_.rUSER[0]'', ``getevkin_.rUSER[1]'' etc. Look at the example in ``dis_kinematics.rmc'' where the kinematic variables Q2 etc were taken directly from the LEPTO model.

Similarly, you can do the same with any MC model.