Thank you guys Indeed, it's better have all programmes in double version anyway.
But now, I may be dreaming, but how 'impossible' is to have one single binary able to work with single or double precision with a simple input option or env variable? At least on Mac one can have more than one binary (for different archs) in 'single' file. And yes, a wrapping script could address that but it's not what I have in mind anyway. Cheers, Alan On Wed, Jun 17, 2009 at 15:16, <gmx-users-requ...@gromacs.org> wrote: >> Jussi Lehtola skrev: >> > On Wed, 2009-06-17 at 13:45 +0200, Berk Hess wrote: >> > >> >> Hi, >> >> >> >> Nothing needs to be double precision. >> >> >> >> Why do you want mdrun in double precision? >> >> The only common reason for this is normal mode analysis, >> >> in which case you need all the tools involved in double precision. >> >> For normal MD simulation there is nearly never a need for >> >> double precision. >> >> >> > >> > If you want to run accurate NVE simulations, double precision is >> > important. If you use thermostats, then there is no need for double >> > precision. >> > >> > >> I can testify to that. Without double precision I've had problems with >> drifting total energy when doing non-periodic NVE. >> > > Indeed, this is correct. > But I guess this falls into the category nearly never. > On the other hand, there are so many Gromacs users nowadays, > there nearly never is nearly never zero users. > >> /Erik >> > Also, I have found that double precision can be nice for energy >> > minimization since it can handle more pathological cases than single >> > precision. Still, usually it doesn't matter much whether the starting >> > point was prepared in single or double precision. >> > > > > That's true. > It would be nice if we could make the single precision code > handle such cases better (force capping?). > > Berk > -- Alan Wilter S. da Silva, D.Sc. - CCPN Research Associate Department of Biochemistry, University of Cambridge. 80 Tennis Court Road, Cambridge CB2 1GA, UK. >>http://www.bio.cam.ac.uk/~awd28<< _______________________________________________ gmx-users mailing list gmx-users@gromacs.org http://lists.gromacs.org/mailman/listinfo/gmx-users Please search the archive at http://www.gromacs.org/search before posting! Please don't post (un)subscribe requests to the list. Use the www interface or send it to gmx-users-requ...@gromacs.org. Can't post? Read http://www.gromacs.org/mailing_lists/users.php