What steps will reproduce the problem?
1. u = Universe("brown.psf", "brown.dcd")
2. print u.trajectory.delta
9.99999974738e-05
3. print u.trajectory.dt
0.0048888208765
4. print u.trajectory.units["time"]
AKMA
5.print
u.trajectory.dt*MDAnalysis.core.units.timeUnit_factor[u.trajectory.units["time"]
]/u.trajectory.skip_timestep
0.0999999974738
What is the expected output? What do you see instead?
for 2:
Expected: 0.0001
Instead: 9.99999974738e-05
Relative Error: 2.52621248364e-08
for 3:
Expected: 0.1
Instead: 0.0048888208765
for 4:
I do not know what I should expect. No units?
for 5:
Expected: 0.1
Instead: 0.0999999974738
Relative Error: 2.52621247254e-08
What version of the product are you using? On what operating system?
MDAnalysis 0.7.5 and MDAnalysis 0.7.4
Linux ubuntu 11.04 AMD 64 2.6.38-13
python 2.7
Please provide any additional information below.
Concerning 4:
The .lam file is in lj units, so the output should be in dimensionless
time units.
Here, the system seems to believes that the data is in AKMA units and converts
internally to some other time unit.
But even when only considering the values for .delta, I still have a relative
error of 2.e-8 even for simple values such as 0.0001.
Note that the error is zero for values of delta = 1.
This error is a pain in the ass, for long timeseries this adds up to more than
one frame.
Original issue reported on code.google.com by
bjrnfrd...@gmail.comon 14 Nov 2011 at 3:36Attachments: