how to plot ellipse in this format?

Question

Hi guys,

I would like to ask how to plot ellipse in such format?? a*x^2+b*y^2+c*x*y+d*x+e*y-1=0

I tried with ezplot and contour and it didn't seem to work. Thank you guys!

Cliff.C

Answer 1

If you use that equation you must satisfy the relation c^2 - 4ab < 0 for it to be an ellipse.

Edit: Also specifying more clearly how it does not seem to work (what you were expecting and what happened) could be useful.

Answer 2

You need to use numeric values for the parameters a through e. Then you can plot the ellipse with ezplot.

Answer 3

see this file on the matlab file exchange: ellipse.m