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Feature #1397

gmx eneconv -offset 1.998 -dt 2 is broken for large times

Added by Mark Abraham almost 6 years ago. Updated over 5 years ago.

Status:
New
Priority:
Normal
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Category:
analysis tools
Target version:
Difficulty:
uncategorized
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Description

For a long trajectory, gmx eneconv -offset 1.998 -dt 2 writes frames with time stamps at

...
16771.998000
16773.998000
16775.998000
16777.996000
16777.998000
16778.000000
16779.996000
16779.998000
16780.000000
...

This is easily fixed by not doing the floating-point modulo arithmetic in single precision. Perhaps some other tools are also affected.


Related issues

Related to GROMACS - Bug #2145: `gmx energy` -skip option yields unexpected subsampling of dataClosed

History

#1 Updated by Mark Abraham almost 6 years ago

  • Description updated (diff)

#2 Updated by Erik Lindahl over 5 years ago

  • Tracker changed from Bug to Feature
  • Target version changed from 5.0 to future

Looking more into this I would argue it is not easily fixed. If we simply switch the modulo arithmetic to double we will be requiring a match to 1e-15, which in most cases will never be true when the input numbers have been provided in single-precision accuracy.

Basically, this comes down to asking for more-than-single-precision accuracy in a single precision version of Gromacs. Not a bad idea, but it's not a bug => changing to future feature.

#3 Updated by Mark Abraham over 2 years ago

  • Related to Bug #2145: `gmx energy` -skip option yields unexpected subsampling of data added

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