Re: few remarks

[Ethan M. <merritt@u.washington.edu>]

On Monday 09 August 2004 11:04 pm, mi...@ph... wrote:
> Bug:
> On x11 (well, I haven't look to other terminals), points in the points and
> linepoints styles are "handicapped" -- look by a screen magnificator (xmag,
> kmag) to points obtained by:
> 
> set size ratio 1
> plot sin(x)/x w point pt 2

That is one strange bug you have found.  The odd thing is that it seems
to be a bug in the X server.   I can run the same gnuplot_x11 executable
on two different machines and get two different results.  My best guess
at the moment is that the key difference is which version of X11 is
running, although it is also possible that it is a difference in the video
driver rather than the version.  The issue is whether the rendering
engine does, or does not, draw the final pixel in a line segment that is
at 45 degrees. Changing the drawing style from CapButt to CapRound
while drawing points fixes this, at least on the machines I have tested.
I can't think of any bad effects from this so I will make the change.
I'm sure someone will speak up if it uncovers some complementary
bug on other X11 display setups.

Meanwhile I notice that the aspect ratio of the plot symbols
scales with that of the current x11 window.  This seems ugly to me,
so I propose to also change the code so that the cross/plus/star/etc
always has a 1:1 aspect ratio, even if the plot in which it lies does not.






> 
> ***
> 
> "help filledcurves" is not very well understandable.
> I propose the following:
> 
>  The `filledcurves` style is only relevant to 2-d plotting. Three variants
>  are possible. The first two take a function or two columns of input data
>  file, and may be tuned by options (see below). The default is `closed`, which
>  treats the curve itself as a closed polygon. The second variant is to fill the area
>  between the curve and a given axis, a horizontal or a vertical line, or a
>  point. The third variant requires three columns of input data file: the x
>  coordinate and two corresponding y coordinates (two curves); then, the area between the
>  two curves is filled.
> 
>  Syntax:
>  	...
> 
>  where the option (the first two variants only) can be
> 
>  ...
> 
>  Example for the third variant:
>  	plot 'data.dat' using 1:3:4 with filledcurves
> 
>  Note: ...
> 
> ***
> 
> postscript terminal contains new option "level2". I propose to add (or
> rather change to) option "level1" -- I guess it is more natural to restrict
> to PS Level 1 printer by saying "set term post level1" rather than
> "set term post nolevel2". (Also, it may become confusing whether
> "PS Level 3" printer is "level2" or "nolevel2").
> 
> ****
> 
> When "make tutorial" (under Linux): File $HOME/.gnuplot should not be read
> -- it may contain an offending command which breaks the make process.
> 
> Could the particular pieces of tutorial/Makefile[.am?] contain something
> like
> 	HOME=/dev/null gnuplot ...
> ?
> 
> ****
> 
> gnuplot.doc contains an example for using new features "title and
> xticlabels":
> 1.
>   plot 'datafile' using 1:(f($2)/$4) title 2 with lines
> 
>   I guess that a more transparent example could be the same as few lines
>   above:
> 
>   plot 'datafile' using 3:4 title 2 with lines
> 
>   (it is not clear what is f($2), and the result is obviously division, not
>   remainder?)
> 
> 
> 2. In gnuplot.doc, I propose that "help xticlabels" go (reference) to the
>   same entry as "help using xticlabels".
> 
> ***
> 
> 
> Currently I have only web access to internet, so I cannot do any change into
> cvs. Thus I'd like to ask others to submit my proposed features, if
> agreed. Thanks.
> ---
> Petr
> 
> 
> 
> 
> 
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-- 
Ethan A Merritt       merritt@u.washington.edu
Biomolecular Structure Center
Mailstop 357742
University of Washington, Seattle, WA 98195