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Someone could tell me please do that I'm doing wrong?

Posted 10 years ago

Hi all, I write for a little help, I have the function

y^2 = x and I turned it to its polar form by the following steps

    ini = y^2 == x /. {x -> r*Cos[x], y -> r*Sin[x]} ;
    conv = Replace[r, Solve[ini, r]][[2]];
PolarPlot[Cot[t] Csc[t], {t, 0, 2 Pi}, 
 PlotRange -> {{0, 80}, {-10, 10}}]

Then attempt to convert it to its form parametric from the polar form but the plot is where the problem arises

conv*Cos[x] (* This is x[t]*)
conv*Sin[x]   (* This is y[t]*)

The problem is the graph the equations parametric I have obtained, someone could tell me please do that I'm doing wrong?

ParametricPlot[{Cot[t]^2, Cot[t]}, {t, 0, 2 Pi}]

Thanks in advance.

POSTED BY: Luis Ledesma
4 Replies

That's right... enter image description here

POSTED BY: Simon Cadrin

Not using an informative subject header, for a start.

POSTED BY: Daniel Lichtblau
Posted 10 years ago

Thank you very much for your help this Nasser it is the graph that he hopes to obtain, also thanks for your council to tabulate I bear it very in mind it might be said that I already did mine.

Luis Ledesma

POSTED BY: Luis Ledesma

I am not able to follow what you are attempting to do. But to find why a plot comes out empty, it is always good idea to look at the data itself you are trying to plot using the Table command and see what is the problem. For example,

  data = N@Table[{Cot[t]^2, Cot[t]}, {t, 0, 2 Pi, Pi/10}]

enter image description here

You can look at the plot of Cot to see its range.

To help ParametricPlot do it, try the MaxRecursion option

 ParametricPlot[{Cot[t]^2, Cot[t]}, {t, 0, 2 Pi}, PlotRange -> {{0, 3}, {-3, 3}}, MaxRecursion -> 15]

enter image description here

POSTED BY: Nasser M. Abbasi
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