gr.xvg files have only 3 digits after decimal point

User discussions
1

Hello,

the “recent” rdf code gives rdf.xvg output files with only 3 digits after the decimal point. This is not sufficient to compute some structural properties (such as the KBI for those who know what it is). Does anyone here knows how to increase the number of digits?

Thanks in advance

A. Perera

2

I see 6 decimals, both in the code and in the output.

For KBI we should output the integral up to r, like the old code did.

3

Thank you for your reply. But I must confess I find it too short to help me. Could you let me know what you mean by code and output? I dont know where is the code, and which code you are talking about (rdf code?). In some versions of my computation I get 5 digits after the decimal point. In some others no. It does not seem to be related to Gromacs version.
And please, dont discuss the KBI issue here - I just mentioned it to justify my query. I am well versed in the KBI topic and I dont want to start a discussion about it here. Just the digit problem please.

I am eager to read more about your input to sort out this digit issue.

Thanks in advance

4

I looked in src/gromacs/trajectoryanalysis/modules/rdf.cpp and see 11,6 as format, so 6 decimals after the decimal point. I ran gmx rdf of version 2025 and get 6 decimals after the decimal point.

Strange to request not to discuss KBI. You loose a bit of information/precision when converting back an RDF to the cumulative RDF. The old rdf tool had cumulative (number?) rdf output precisely for computing KBIs.

5

I can see the 11,6 format in the code as you mention, but I never got 6 digits for the rdf so far. Perhaps there are ENV environment variables that restrict the output. I use the code installed by the admistrator, so I have to check that.
As to the KBI issue, if you know this topic, then you know that it is a Grand Ensemble quantity, but in practice it is computed in the isobaric one, which creates lots of problems. I require highy quality Fourier transform of the rdf, so it is primordial to have more than 3 digits for the rdf. There you go.
Thanks for your input.