[Rivet] AGILe and PYTUNE

[Gavin Hesketh]

Hi,
that's neater than my idea, but I still had to hack the code a little to 
call pytune rather than pygive. Now I can pass agile the following 
parameter file:

PYTUNE 103
PARP(64) 2

PYTUNE has to come first in the list, but that's fine. The hacks I used:

FPythiaWrapper.hh:

   #define FC_PYTUNE FC_FUNC(pytune, PYTUNE)
   void FC_PYTUNE(int*);

....

void call_pytune(int tune);




FPythiaWrapper.hh:

void call_pytune( int tune ) {
   pytune_( &tune );
}




FPythia.cc, modify the setParam function:

   // Set a parameter with a string value
   bool FPythia::setParam(const string& name, const string& value) {
     Generator::setParam(name, value);
     if(name=="PYTUNE")
       call_pytune(atoi(value.c_str()));
     else {
       const string pygive_input(toUpper(name) + "=" + value);
       call_pygive(pygive_input.c_str());
     }
     return SUCCESS;

   }


cheers,
	Gavin



On 03/12/10 19:41, Peter Skands wrote:
> Hi,
>
> MSTP(5) is only intended as a convenience for users that *just* want a
> specific tune. It is 100% equivalent to the construction:
>
> CALL PYTUNE(ITUNE)
> CALL PYINIT(...)
>
> For users that desire more flexibility (or me, when I make new tunes),
> it is completely possible to take control back and make a construction
> like:
>
> C...Set base tune
> CALL PYTUNE(ITUNE)
> C...Insert user modifications here
> CALL PYGIVE('PARP(64)=2D0')
> ...
> C...Force PYINIT to *not* call PYTUNE
> CALL PYGIVE('MSTP(5)=0')
> CALL PYINIT(...)
>
> Would that work for you?
>
> Peter
>
> On 12/3/10 7:21 PM, Andy Buckley wrote:
>> On 03/12/10 16:53, Gavin Hesketh wrote:
>>> Dear AGILe authors,
>>> I've just been playing around with the fortran pythia. I'm sure you know
>>> recent versions have the PYTUNE function, which allows you to select any
>>> of the "standard" tunes, by setting the MSTP(5) parameter.
>>>
>>> But, if I want to use this feature while also varying one parameter that
>>> is part of that tune, eg by passing the following parameter file when I
>>> call agile-runmc:
>>>
>>> MSTP(5) 105
>>> PARP(64) 2
>>>
>>> then my choice of PARP(64) is overwritten by PYTUNE. iirc, he way to
>>> avoid this is to set MSTP(5), call PYINIT, then set the other
>>> parameters.
>>>
>>> I wondered if anyone had figured out how to do such a thing with agile,
>>> or if I simply can't use the MSTP(5)/PYTUNE functionality and have to
>>> set all the tune variables by hand?
>>
>> Hi Gavin,
>>
>> As far as I'm aware, PYTUNE will stomp all over any user-specific
>> settings, so slight variations on PYTUNE tunes are not possible. I
>> mentioned this to Peter Skands (CC'd) a while ago, so maybe the latest
>> version of PYTHIA does now support customising settings on top of
>> PYTUNE... Peter?
>>
>> If not, is it possible to structure AGILe's calls to the PYTHIA routines
>> such that PYTUNE will be called first (with a special-case param passing
>> of MSTP(5)) and then PYGIVE be called for all the other params?
>>
>> I'll very happily make an AGILe patch release to incorporate this (as
>> well as any new Fortran generator interfaces that people supply...
>> MC at NLO, anyone?!)
>>
>> Andy
>>