[gmx-users] Inaccurate time frame

[Mark Abraham]

On 12/07/10, Hsin-Lin Chiang  <jiangsl at phys.sinica.edu.tw> wrote:
>  Hi,
> 
> My time unit is 1ps and today I have 300ns data generated by parallel simulation.
> I use trjconv -split 1000 on my trajectory but get the truncated end at t= 5000.00000
> Theoretically it should stop at t= 1000.000
> I found that I don't have t= 1000.00000 frame but have t= 1000.00006, 2000.00012, 3000.00024, and t= 4000.00024.
> 
> I know I can add -timestep 1 to solve this problem and let file can be truncated at t= 1000.00006.
> 
> How does this kind of inaccurate time frames happen?
> Is this trajectory a wrong result?
> 
I just wrote a FAQ+wiki page for this, since it gets asked a bit. See http://www.gromacs.org/Documentation/Floating_Point_Arithmetic

trjconv -skip -sep is a more robust approach here

Mark
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