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I am trying to plot the following parametric equation in gnuplot:

fx(t) = -35*cos(t) + 65*cos(-.35*t)

fy(t) = -35*sin(t) - 65*sin(-.35*t)

I am not using much more code than pasted above. The result is fairly ugly.It is very angular, and obviously there must be some command to smooth it out.

I have tried to use commands like smooth cspline and smooth bezier to no avail.

How do I make a nice smooth graph of this function in gnuplot?

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I cant answer your question; but the graph is quite pretty, as produced by JSXgraph. I'm tempted to post it. –  David Mitra Jan 11 '13 at 15:57

2 Answers 2

up vote 1 down vote accepted

Just change the samples value typing, for example,

set samples 10000

Here is the complete command:

set parametric
set xrange [-110:110]
set yrange [-110:120]
set trange [0:300]
set samples 10000
plot -35*cos(t)+65*cos(-.35*t),-35*sin(t)-65*sin(-.35*t)

enter image description here

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1  
Yes, that's it. I was using the samples with values of 30 or 60. I had no idea I had to go that high. I tried it with 20000, but there was no difference. It would be nice to know how to make the graph with the smoothest possible lines...it seems that after 10000 it is as smooth as it can get. –  Paul Jan 12 '13 at 3:59

This link may help to answer your question http://nrlug.puhep.res.in/GLUE/Packages/plot/gnuplot/parametric.html

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