Re: [Gnuplot-info] Outputting Coordinates

[Thomas S. <t.s...@fz...>]

use 'set table':

set polar
r(t)=4.*cos(3.*t)
set trange [0:pi]
set table
plot r(t)
unset table


Soothfast wrote:
> 
> Hi.  I try to be self-sufficient, I really do, but I can't figure out my
> problem.
> 
> So, I successfully installed gnuplot on the MacBook Pro.  I've been using
> pgfplots for months, in conjunction with tikz, to product graphs both
> qualitative and quantitative in LaTeX.  But pgfplots has limitations, like
> it can't graph polar curves for starters.  To graph r=4\cos(3\theta) this
> is what I did:
> 
> \begin{tikzpicture}[>=latex,scale=0.60]
> 	\draw[very thin,gray8] (-4.3,-4.3) grid (4.3,4.3);
> 	\draw[<->] (-4.5,0) -- (4.5,0) node[below]{$x$}; 
> 	\draw[<->] (0,-4.5) -- (0,4.5) node[left]{$y$} ;
> 	\draw (-3,6pt) -- (-3,-6pt) node[below]{$-3$};
> 	\draw (6pt,3) -- (-6pt,3) node[left]{$3$} ;
> 	\draw[thick,blue]
> 		plot[smooth,tension=0.6] coordinates{(0,0) (-.37,-.23) (-1.1,-.82)
> (-1.67,-1.47) (-2.05,-2.12) (-2.25,-2.83) (-2.14,-3.33) (-1.79,-3.52)
> (-1.30,-3.34) (-0.78,-2.80) 
> 		(-0.33,-1.93) (-0.06,-0.84) (-0.01,0.35) (-0.19,1.50) (-0.58,2.47)
> (-1.08,3.16) (-1.60,3.49) (-2.02,3.45) (-2.24,3.07) (-2.17,2.43)
> (-1.79,1.64) (-1.11,0.83) 
> 		(-0.18,0.11) (0.88,-0.42) (1.96,-0.70) (2.91,-0.72) (3.38,-0.61)
> (3.79,-0.39) (3.99,-0.09) (3.93,.23) (3.63,.5) (3.1,.69) (2.39,.74)
> (1.57,.62) (.7,.34) (0,0)};
> \end{tikzpicture}
> 
> This is the kind of graph I want for notes in calculus that I'm creating,
> and it doesn't even involve pgfplots at all; but the problem is all those
> ordered pairs had to be entered in manually (I got them off a TI-83
> calculator).  Eventually I want to use gnuplots for grand and glorious
> things, but for now I just want to know how to get it to create a list of
> ordered pairs for me, right on the terminal, that I can copy/paste into a
> .tex file in the manner you see above.  I understand that pgfplots can be
> used to call on gnuplot to do this automatically "behind the scenes", but
> then I couldn't necessarily give someone my code and expect it to work for
> them unless they have gnuplot installed as well (along with all sorts of
> technical reconfiguring to get their TeX distribution to talk to gnuplot). 
> I want explicit data in my file, and I just want a dumb way to generate a
> list of ordered pairs in the terminal for copy/paste purposes.  I've
> scoured the internet and cannot find anyone talking about this.  In the
> case of r=4\cos(3\theta) the ordered pairs should preferably be in
> rectangular coordinates, like a TI-83 gives.
> 
> Many thanks for any help in this regard.
>  
> 

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