[Rd] call fortran in R

[Bill Northcott]

On 04/08/2005, at 8:00 PM, Sebastien Durand wrote:
> I used a mac G5, R.2.1.1, and G77 3.4.4 and I would like to use and
> call a fortran subroutine.
> The trouble is that it seems I am not able to correctly load the
> compiled code.

.................

>      base
> 2  /Library/Frameworks/R.framework/Resources/library/grDevices/libs/
> grDevices.so
> 3          /Library/Frameworks/R.framework/Resources/library/stats/
> libs/stats.so
> 4      /Library/Frameworks/R.framework/Resources/library/methods/libs/
> methods.so
> 5   /Users/sebas/Desktop/Fortan_kmeans/kmeans3.so
>
>     Dynamic.Lookup
> 1           FALSE
> 2           FALSE
> 3           FALSE
> 4           FALSE
> 5            TRUE

I really wish someone would make these issues clear in MacOS R  
documentation.

MacOS X 10.3 Panther uses gcc-3.3 as its default compiler.  The R  
binary is built with gcc-3.3 and g77 3.4 so that it will run on Panther.

MacOS X 10.4 Tiger uses gcc-4.00 as its default compiler.  This  
causes two problems.
1.  Fortran objects built with g77 cannot be linked with C/C++  
objects built with gcc-4.0.  So an R package with a mixture of C and  
Fortran code will very likely fail at some point.
2.  Even if you specifically invoke gcc-3.3 and g77 the code will  
still fail to link because it needs a symlink /usr/lib/ 
libcc_dynamic.dylib which points to libgcc.a.  This link is missing  
if the default gcc-4.0 is the selected compiler.  (It is missing  
because it does not work with gcc-4).

If you want to build Fortran source packages on Tiger using the R  
binary distribution, you need to to do
'sudo gcc_select 3.3'

That command will make gcc-3.3 the default compiler and reinstate the  
symlink, which recreates the environment in which the R binary was  
built.   You can always go back to gcc-4.0 with 'sudo gcc_select 4.0'.

Bill Northcott