Using the ellipse graph.

11 vues (au cours des 30 derniers jours)
John Lutz
John Lutz le 30 Sep 2017
In polar coordinates (r,t), the equation of an ellipse with one of its foci at the origin is r(t) = a(1 - e2)/(1 - (e)cos(t)) I'm confused how to set this up, as I have never occurred an ellipse graph before. where a is the size of the semi-major axis (along the x-axis) and e is the eccentricity. Plot ellipses using this formula, ensuring that the curves are smooth by selecting an appropriate number of points in the angular (t) coordinate Thank you.
function untitled3
a = 1/2(b);
e = 0.5;
t = linspace(0,2*pi);
r = a(1 - e.^2)./(1 - (e)*cos(t));
plot(r,t)
axis equal
end

Réponses (3)

Image Analyst
Image Analyst le 30 Sep 2017
You need to define b using a and e, not assume b is already defined like you did.
  1 commentaire
John Lutz
John Lutz le 30 Sep 2017
Still does not work, really confused on this.
t = linspace(0,2*pi);
e = 2*pi;
a = 1/2.*(2*pi);
r = (a.*(1 - e.^2) ./ (1 - ((e)*cos(t))));
axis equal
plot(r,t);
also this doesn't work either, tried many times to get this to work but it doesn't.

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Henry Giddens
Henry Giddens le 30 Sep 2017
Your equation ends up with some negative values - (which I'm not sure can be correct?), but if you are using polar coordinates, then use the polarplot or polar commands:
polarplot(t,abs(r))

Ali Nafar
Ali Nafar le 13 Juin 2019
L=0.5;
e=0.5;
phi0=0;
phi=linspace(0,2*pi);
rho=L*(1-e^2)./(1-e*cos(phi-phi0));
polar(phi,rho)

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