[gmx-users] Precision question...

[David van der Spoel]

Stéphane Teletchéa wrote:
> I can compile gromacs either in single or double precisions, and 
> according to the manual, using single precision is sufficient for 
> simulations. Is there any gromacs-related paper about this ?
> 
> If i used 32-bit systems and 64-bits systems, is it correct to say :
> 
> single precision 32-bits = real single precision
> double precision 32-bits = single precision 64-bits
> double precision 64-bits = 4 * real single precision
> 
> I mean : is the statement correct (in theory) and are all routines 
> taking this precision into account ?
> 
No, 32/64 bits is not related to floating point precision. Single = 32 
bits floats, double = 64 bits floats.


> Thank you in advance for your 'precisions' :-)
> 
> Stéphane


-- 
David.
________________________________________________________________________
David van der Spoel, PhD, Assoc. Prof., Molecular Biophysics group,
Dept. of Cell and Molecular Biology, Uppsala University.
Husargatan 3, Box 596,  	75124 Uppsala, Sweden
phone:	46 18 471 4205		fax: 46 18 511 755
spoel at xray.bmc.uu.se	spoel at gromacs.org   http://xray.bmc.uu.se/~spoel
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