6
$\begingroup$

This article from The Guardian discusses Isaac Newton's investigation of the properties of the curve $x^3 – abx + a^3 – cy^2 = 0$, where $a, b$ and $c$ are constants. The image above is the curve of this equation when $a = 1, c = 4$ and $b$ ranges from –8 to 8.

The image seemsextremely aesthetic to me , almost artistic work. I'd have image on the wall like a poster, but with

ContourPlot[
  Evaluate@Table[x^3 + b x == 4 y^2, {b, -8, 8, 1}], {x, -5, 5}, {y, -5, 5}, 
  Frame -> None, ImageSize -> 600,  ContourStyle -> Black, PlotPoints -> 20]

I can not reproduce that image. The result is a bit different. Can someone please explain what is wrong with my code?

$\endgroup$

closed as off-topic by MarcoB, Henrik Schumacher, Bob Hanlon, AccidentalFourierTransform, Johu Oct 10 '18 at 6:31

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "This question arises due to a simple mistake such as a trivial syntax error, incorrect capitalization, spelling mistake, or other typographical error and is unlikely to help any future visitors, or else it is easily found in the documentation." – MarcoB, Henrik Schumacher, Bob Hanlon, AccidentalFourierTransform, Johu
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    $\begingroup$ Well, you seem to have done your substitutions incorrectly. The correct equation you should plot is x^3 - b x - 4 y^2 + 1 == 0. You are missing a constant, and the b x term seems to have the wrong sign. If you change the equation to the one I showed, the plots is much more similar to the one in the link. You might also want to restrict the range of x to e.g. {x, -5, 3.5}. $\endgroup$ – MarcoB Oct 9 '18 at 16:26
  • $\begingroup$ I'm sorry, I do not know how I managed to make such a ridiculous mistake. $\endgroup$ – Darko G Oct 9 '18 at 17:07
7
$\begingroup$

You are plotting wrong equation, See this.

a = 1; c = 4;
ContourPlot[
Evaluate@Table[x^3 - a*b *x + a^3 - c*y^2 == 0, {b, -8, 8, 0.5}], {x, -3., 
3.}, {y, -3.5, 3.5}, Frame -> None, ImageSize -> 600, 
ContourStyle -> Directive[Thickness[0.0015],PlotPoints -> 20]

I have changed the step size of $b$ and plot range of axis to mimic with the figure in that link.

It plots as: enter image description here

$\endgroup$
  • 1
    $\begingroup$ You can maintain sharpness while increasing the number of steps ({b, -8, 8, 1/2}) by using ContourStyle -> Directive[Thin, Black] $\endgroup$ – Bob Hanlon Oct 9 '18 at 17:14
  • $\begingroup$ @BobHanlon, Modified, Thank you $\endgroup$ – math Oct 9 '18 at 18:25

Not the answer you're looking for? Browse other questions tagged or ask your own question.