Re: [Gnuplot-info] problems with polar plot: no negative axis labels

[Johannes R. <ja...@ho...>]

Thanks for the suggestion, but rrange is the wrong thing: In polar mode
gnuplot> set rrange [0:10]
gnuplot> plot t
does the same thing as

gnuplot> set rrange [-5:5]
gnuplot> plot t-5
(in other words, the lower bound of the rrange will always correspond to the origin, and the rest is shifted)

I'm just wondering, because if I look at the great page
http://t16web.lanl.gov/Kawano/gnuplot/polar-e.html
(which is, by now, a bit outdated, but still very useful) I see that this behaviour must have changed some versions ago.  While I admit that this behaviour has some justification, at least for my applications it does not make sense.  And using a multiplot insert is a bit overkill just for plotting the axis labels.

Meanwhile I found another solution to my problem: Specifying the axis labels one by one does work, e.g:
set xtics ("7" 7, "6" 6, "5" 5, "4" 4, "3" 3, "2" 2, "1" 1, "0" 0, "-1" -1, "-2" -2, "-3" -3, "-4" -4, "-5" -5)
plot t

Cheers,

Johannes Rauh

> From: gu...@if...
> 
> As Thomas Sefzick has shown, you can play with 'rrange', up to making
> its lower bound negative.
> BUT, note:
> 1. both coordinates will be non-monotoneus then, and worse yet
> 2. the shape of your curve may be substantially different  (test Thomas'
>      example, see the result, and continue with:
>      > gnuplot> set rrange[*:*]
>      > gnuplot> replot
>      )
> Maybe you should consider making your polar plot to be an insert to the
> regular picture, in usual, Cartesian coordinates.  For this you should
> rather consult/consider  the 'multiplot'  mode.
> 
> Cheers,
> Marek Gutowski
> 
> Johannes Rauh wrote:
> > @Mauricio: Thanks for the workaround to this "feature" ;-)
> > 
> > @Marek: Thanks for the explanation.
> > 
> > Is it a feature I can deactivate? My problem is the following: I want to 
> > plot something in the x-y-plane, using polar coordinates, so having a 
> > minus sign would be very nice.
> > 
> > Cheers,
> > Johannes Rauh
> > 
> >  > It's not an error, it's a feature. The numbers you read are NOT
> >  > y-values - you're plotting in polar coordinate system, aren't you?
> >  > So, what you see, is a set of r-values, and those are non-negative.
> >  >
> >  > Cheers,
> >  > Marek Gutowski
> >  >
> >  > Johannes Rauh wrote:
> >  > > Hello,
> >  > >
> >  > > I have a problem with gnuplot: When I do a polar plot, like e.g.
> >  > >
> >  > > set polar
> >  > > plot cos(t)
> >  > >
> >  > > the minus signs are missing on the axis, so the labels at the y-axis go
> >  > > 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5
> >  > >
> >  > > Any i! deas?
> >  > > Kind regards,
> >  > >
> >  > > Johannes Rauh
> 
> 
> -- 
> Marek W. Gutowski
> Institute of Physics, ON-3.2, Al. Lotnikow 32/46
> 02-668 Warszawa, POLAND, tel. +48-22-0228436601 ext. 3122
> == To talk or not to talk?  Yes, talk, plain ASCII please ==
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~