[gmx-users] Hessian matrix

[Erik Lindahl]

It's 10*sqrt(GMX_REAL_EPS), where GMX_REAL_EPS is the tolerance in  
the current precision.

Cheers,

ERik

On Oct 11, 2005, at 2:41 PM, Nguyen Hoang Phuong wrote:

>
> Dear All,
>
> in gromacs, the matrix elements of the Hessian matrix are numerically
> calculated by using the finite differentiation method which I think  
> like
> this (please correct me if it is wrong)
>
> d^2f/dx^2 = {f(x+dx) - 2f(x) + f(x-dx)}/(2*dx)
>
> I would like to ask if some of you know what is value of the  
> interval dx?
>
> Thanks in advance.
>
> Phuong
>
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-----------------------------------------------------------
Erik Lindahl  <lindahl at sbc.su.se>
Assistant Professor, Stockholm Bioinformatics Center
Stockholm University, SE 106 91 Stockholm
Phone: +46 8 5537 8564     Fax: +46 8 5537 8214