R: RE: R: RE: R: RE: R: RE: R: RE: R: Re: R:[gmx-users] Tabulated potential - Problem

[Mark Abraham]

Berk Hess wrote:
> 
> 
>  > Date: Fri, 2 Oct 2009 06:10:37 +1000
>  > From: Mark.Abraham at anu.edu.au
>  > To: gmx-users at gromacs.org
>  > Subject: Re: R: RE: R: RE: R: RE: R: RE: R: RE: R: Re: R:[gmx-users] 
> Tabulated potential - Problem
>  >
>  > Berk Hess wrote:
>  > > Ah, I thought the sentence in one of my previous mails was clear 
> enough:
>  > > "The points in the table_b.xvg file should be equally spaced.
>  > > grompp assumes equal spacing, but does not check this."
>  > >
>  > > I think "should be" and "must be" are equivalent in this context.
>  > > But we can clarify the manual, and add a check in grompp.
>  >
>  > It's close, but in general there is a shade of certainty conveyed by
>  > "must" that is additional to that of "should". The dictionary I have to
>  > hand contrasts "to be obliged or compelled to, as by some constraining
>  > force or necessity" with "to denote duty, propriety, expediency"
>  > respectively. Wiktionary agrees - http://en.wiktionary.org/wiki/must. I
>  > am aware of usage in a body of law where failure to follow a direction
>  > qualified by "must" carries a more severe consequence than failure to
>  > follow a direction qualified by "should".
>  >
>  > Berk is correct in this context, however. The only relevant qualities of
>  > the table are that it be accurate and reasonably efficient. A user
>  > failing to follow "should" would be making an unwarranted assumption
>  > that accuracy and/or efficiency was compromised only to a negligible
>  > degree. "must" is slightly superior in such a context where no purpose
>  > is served by the distinction with "should," and the reader might err
>  > more often when "should" is used. Manual section 6.7.1 certainly
>  > expresses the idea that equal spacing of table points is normal and
>  > expected, but there is no statement which conveys a suitable degree of
>  > definiteness. That could be improved.
>  >
> 
> I am aware of these subtle differences.
> I am not a native English speaker (although I did live in Australia
> for 3.5 years during my childhood). But I personally do not like
> a manual description which repeatedly uses the word "must",
> it just doesn't sound very friendly. I strongly prefer "should".

Fair point. Consistency would require a large number of uses of "must" 
which would be tedious to write and confronting to read.

Mark

> But we could also use something like "has to have".
> Anyhow, I'll put a check in grompp, so the user will get a fatal error
> and can not proceed, even if he/se interprets the manual differently
> from intended. Such a check doesn't have any disadvantages (except
> for requiring 5 minutes of coding and checking) and also help to detect
> mistakes in script generating tables etc.
> This is becoming more important, as more and more people start using
> numerically derived potentials.
> 
> Berk
> 
>  > Even the use of language can be as exacting as the methods described by
>  > it :-) I tied myself in knots last weekend with an incorrect use of
>  > "abjure" instead of "adjure"...
>  >
>  > Mark
>  >
> 
> 
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