[gmx-users] ic vs gcc : strange results

[Erik Lindahl]

HI Michel,
>
>  I don't get the same output when running the same benchmark with an 
> intel compiled or a gcc compiled version of gmx 3.1.4 on an opteron. 
> The intel version makes the system explode, gcc not.
>
>  However I recompiled only mdrun with icc, whereas grompp is gcc. 
> Could this create problems ?
>
>  Do the fftw libraries have to be compiled with the same compiler as 
> mdrun ?

It depends on the compiler and version. The intel compiler does claim 
to have some sort of compatibility with gcc-style objects, but to be 
safe you should use the same compiler everywhere (including libraries).

>  A related question : can the .tpr file be used safely on another 
> architecture, or does one need to use the local grompp every time ?

All gromacs input/output files are portable, including between 
architectures with different endian or floating point precision. In 
fact, one of the cool things with the XDR formats is that you don't 
even need to assume IEEE754 floating-point formats.

So, you can just go ahead and use the tpr on e.g. a VAX or PDP-11 :-)

Cheers,

Erik