[pstricks] drawing implicit (polar) plot

[Herbert Voss]

Arnaud Schmittbuhl wrote:

> I don't know how to draw an implicit polar plot. I'm interesting in
> plotting this one, useful in fluid mechanics,
> 
> (r^2 -1/r)sin^2\theta = 1

there is in general no possibility to handle implicit defined
equations with psplot.

But it is the same as the special cubic equation

r^3 - r/sin^2\theta -1 = 0

which could be solved with the formula of Cardano.
Do you have any website where I can see the graphic
of this equation?

Herbert


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