[gmx-users] Number of simulated annealing points

[Mark Abraham]

Hi,

My guess is that you're fine. MAXPTR is probably just a hangover from
someone who didn't want to allocate memory dynamically.

Mark

On Fri, 1 Apr 2016 00:50 Tim Moore <tcmoore3 at gmail.com> wrote:

> I went back and tried to change MAXPTR to a larger value - I then get a
> different error saying input lines can only contain 4095 characters. After
> digging around the source code a bit more, I found this came from a defined
> constant STRLEN in src/gromacs/utility/cstringutil.h
> <
> https://github.com/gromacs/gromacs/blob/f3602aa73c3012363cea7013f28458754a9debdb/src/gromacs/utility/cstringutil.h
> >*.
> *I updated this to a larger value to accommodate my long lines in the mdp
> file. After re-installing, I can successfully grompp my input file, and it
> seems to be running fine.
>
> I'm assuming since make check passed without errors, I should not be
> concerned about any hidden, funky behavior. Is this a safe assumption? And
> is there any reason why setting STRLEN to a much larger number is a bad
> idea?
>
> On Wed, Mar 30, 2016 at 1:34 PM, Tim Moore <tcmoore3 at gmail.com> wrote:
>
> > Hi,
> >
> > I'm currently simulating bilayer systems, where our equilibration scheme
> > involves randomly adjusting the temperature to values within a given
> range.
> > The temperatures can be predetermined, so the we can use the simulated
> > annealing module within GROMACS. However, the maximum number of allowed
> > temperatures in simulated annealing is 254 points, meaning we can only
> use
> > 254 points before the cycle starts over (using periodic annealing). I
> need
> > many more set points than that, so this is a problem. I see in the source
> > code there is a parameter MAXPTR = 254 that defines the maximum number of
> > elements allowed. This brings me to my question: is there any reason to
> NOT
> > change this to a larger number to accommodate the larger number of
> > temperature points I need? I see two easy workarounds, the first being to
> > increase MAXPTR; the second being make a new parameter MAXPTR2 and use
> that
> > only for the str_nelem() calls associated with the annealing. Is either
> of
> > these preferred over the other, or is there a better solution? Also, what
> > is the motivation for setting MAXPTR = 254 - is it some sort of
> > optimization? Will setting MAXPTR to a higher value hurt performance?
> >
> > Thanks,
> >
> > --
> > Tim Moore
> >
>
>
>
> --
> Tim Moore
> --
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