Re: ROOT files from FORTRAN

From: Valery Fine (fine@mail.cern.ch)
Date: Mon Sep 29 1997 - 18:34:16 MEST


> Dear rooters,
> Is it possible to write ROOT files directly from FORTRAN?
> In principle i can write ntuple and then transform it to root file 
> but it is not convinuent and requres CERN libraries just to make 
> some temporary file.

   It is possible with some special implementation of Hbook2Root 
interface (based on the CFortran interface from ftp@zebra.desy.de for 
example).

   I've pointed with my previous reply one may create this 
interface and then link his old Fortran code against of this library 
instead of "standard" HBOOK.LIB coming with CERNLIB 

  This way the Fortran code calling HBOOK1 will create the REAL ROOT 
object. HFILL will fill it. HROUT write it out, etc.
   
  There is an argument whether it is worth. But just to make you 
sense I did a dummy version of such sort of the interface and even 
check it with the "standard" CERNLIB HBOOK example 1. (see 
attachment). It does contain the REAL implementations  of 
HBOOK1, HBOOK2,HFILL,HPRINT, HLIMIT,HDELET.

   It works. Just try to compile and link all three attachments
together.

  The FULL implemetation needs writing out about 250 functions. 
I estimate it takes about 15 min/function=0.25 hours/fun = 
250*0.25 = 60 hours = 12 days = 2 man-weeks to complete.(Don't 
forget to add some  amount to maintain this code as well).


      With my regards,
                                 Valery


Dr. Valeri Faine (Valery Fine)
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CERN                             FAX  : +41 22 767 7155
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