09/11/2002: FD
For linking at Jlab, use one of the following CERN_ROOT variables:
  CERN_ROOT=/apps/cernlib/i386_redhat72_egcs/2001
or
  CERN_ROOT=/apps/cernlib/i386_redhat61/99

  CERN_ROOT=/apps/cernlib/i386_redhat72/2001 (i.e. using gcc3)
  doesn't seem to work so far (this is a cernlib problem, not a simc
  or absoft problem) 

07/11/2001: FD
I have ported Simc to Linux using the Absoft compiler. This
is a commercially available compiler which is installed at Jlab under
the ifarm machines.

( Presumably any commercially or freely available Fortran compiler under
Linux would do, provided it supports compilation of structures and records
under Fortran. This, unfortunately, excludes the popular g77, it does
not support these features and according to its developers todo list, these
features do not have high priority on their list. ) 

The current version of the Absoft Fortran compiler at Jlab is
FORTRAN 77 Compiler 4.6, Copyright (c) 1987-1999, Absoft Corp.

Preparations:

You need to define the following Environment variable in your 
.cshrc/.login or whereever you define environments:

setenv ABSOFT /apps/absoft/PRO/usr/absoft

or whereever your absoft compiler directory is located.


The only incompatibility is in the include file histogram_init.inc:
diff ./histograms_init.inc ../../Linux/SIMC_070701/histograms_init.inc
10c10
<         real*8        buf(nHbins)/nHbins*0./
---
>         real*8        buf(nHbins)

The original code declares the array buf and initializes it on the fly.
The initialization takes place within the declaration of a structure.
This, apparently, is too complicated for the Absoft compiler.  The
workaround is to drop the initialization and, since we use a flag to tell
the compiler to use static initialization of arrays, it doesn't matter
here, it initializes the array to contain 0.0.  
Thus, you would most likely want to save the original file 
  cp histograms_init.inc histograms_init.inc.org 
and make this change only for the Linux version.

There are few other general minor changes, which all result in the somewhat
poorer parsing capabilities of the Absoft compiler. These are all safe
to do in the general version and would not affect the behaviour of simc
und SunOS, OSF1 or Linux:

-- Generally, max, min intrinsic functions want to have arguments of type
   double precision.
-- The compiler cannot resolve statements like
   q22*-1e6 
   but can resolve
   -q22*1e6, -1.*q22*1.e6 , q22*(-1.e6)
-  The compiler is picky about the order of statements in the 
   declaration block, ie data statements in general need to be 
   placed at the end of the declaration block.


If John hasn't taken care of them yet, you need to change right now
in the version I downloaded on July 10th:

Makefile:
<   INCLUDES=-I.,..,./sos,./hms,$(Csoft)/SRC/INCLUDE 
---
>   INCLUDES=-I.,..,./sos,./hms,./hrsr,./hrsl,$(Csoft)/SRC/INCLUDE 

simc.f:
diff ./simc.f ../../Linux/SIMC_070701/simc.f
668c668
<      >                (100.*ncontribute_no_rad_proton/max(float(ncontribute),0
.1))
---
>      >                (100.*ncontribute_no_rad_proton/max(dble(ncontribut
e),0.1d0))

eekeek.f:
diff ./eekeek.f ../../Linux/SIMC_070701/eekeek.f
28c28
<       q22=q22*-1.e+06
---
>       q22=-q22*1.e+06
161c161
<       q22=q22*-1.e+06
---
>       q22=-q22*1.e+06

mt19937.f: move the data statements to the end of the declaration block

diff ./mt19937.f ../../Linux/SIMC_070701/mt19937.f
116,117d115
<       data   mti/N1/                  !mti==N+1 means mt[N] is not initialized
< 
119d116
<       data mag01/0, MATA/
121d117
< 
123a120,125
> 
>       data   mti/N1/                  !mti==N+1 means mt[N] is not initialized
> 
>       data mag01/0, MATA/