Re: clunky fn plots

[Juhász P. <pet...@gm...>]

On Tue, 2011-10-11 at 19:49 +0200, pl...@pi... wrote:
> On 10/11/11 19:21, sfeam (Ethan Merritt) wrote:
> > On Tuesday, 11 October 2011, pl...@pi... wrote:
> >> On 10/11/11 18:42, sfeam (Ethan Merritt) wrote:
> >>> On Tuesday, 11 October 2011, pl...@pi... wrote:
> >>>> Hi,
> >>>>
> >>>> I was under the impression that plotting functions and data in the same
> >>>> plot command meant the interval for the fn plot would follow the
> >>>> datafile.
> >>>
> >>> The sample interval for function plots is controlled only by the
> >>> "set sample" and "set isosample" commands.   There is no connection to
> >>> the number or location of points in any of the data plots.
> >>>
> >>> 	Ethan
> >>>
> >>
> >> Many thanks Ethan .
> >>
> >> in fact my college had just discovered that setting via wgnuplot's menus
> >> . It would have taken me a lot longer on linux digging blindly thought
> >> the help.
> >
> > Then the most useful thing might be for you to suggest where in the help
> > system to add this information.  Where did you look first?  Would that be
> > a logical place to add mention of "set sample"?
> 
> Well , I think that is half (most of ) the discovery problem. Why would 
> I think of looking for sample or set sample without already know the answer?
> 
> This term is presumably short for sample rate, but when a _user_ is 
> thinking of plotting a function he will not consider that he is 
> "sampling".  The term does not evoke what it does.
> 
> "help function" is very terse and does not deal directly with plotting 
> functions nor does it direct you to that sort of info with a "see also".
> 
> "help plot" does not even have a subtopic about functions.
> 
> help plot > ranges does not cover it either, though there would be some 
> logical reason to look there.
> 
> Indeed , could this actually be set as a extension to the range specifier ?
> 
> 
> Any , or perhaps all those places could be used to at least point the 
> user with a "see also" comment.
> 
> I hope those suggestions are useful.
> 
> best.
> 

An idea I've just had: 
perhaps it would be worth introducing a feature like "man -k" in *nix
or ?? in R. 

If the user were looking for the way to do something but didn't know
where he should look, he could use a hypothetical new "searchhelp" or
"helpindex" command with some keyword related to his troubles, and
gnuplot would list the relevant help topics.


By the way, an answer to your original question would be

plot "datafile" using 1:2, "" using 1:(f($1))

which would evaluate your function at exactly the same points as the
datafile.

Péter Juhász