[gmx-developers] Use of invsqrt with tables
hess at kth.se
Wed Mar 23 13:31:09 CET 2016
But avoiding the inversion is not possible, since you need to multiply
the scaling force by the normalized distance vector.
On 2016-03-23 13:00, David van der Spoel wrote:
> In all versions of gromacs the distance between two nonbonded atoms is
> computed as
> rinv00 = gmx_invsqrt(rsq00);
> r00 = rsq00*rinv00;
> This is fine when we use Lennard Jones and Coulomb, but not when using
> table potentials which do not necessarily have singularities at r = 0.
> I would therefore propose to replace the statements by a normal sqrt
> in all innerloops using tables.
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