```Date: Jan 19, 2013 6:50 PM
Author: Jessica
Subject: Re: create polygon coordinates

"Roger Stafford" wrote in message <kdera0\$71t\$1@newscl01ah.mathworks.com>...> "Jessica" wrote in message <kdenag\$nth\$1@newscl01ah.mathworks.com>...> > I have coordinates such as this:> > > > 384 360 60 69> > > > that represent the left, top, width, and height of an ellipse. How can I turn these values into a list that specifies a polygon?> > > > I would like to use this polygon list to find out whether particular X and Y coordinates fall inside this ellipse:> > > > k_inside1= inpolygon(X_Coordinate, Y_Coordinate, X_Polygon3, Y_Polygon3);> > > > Thanks!> - - - - - - - - ->   It seems a shame to approximate an ellipse with a polygon to see if points lie inside it, when a direct test with the simple equation of the ellipse would accomplish the same thing with much better accuracy and simplicity.> >   However, here are n vertices of a polygon approximating an ellipse.  Let the ellipse be defined by the equation> >  (x-x0)^2/a^2 + (y-y0)^2/b^2 = 1> > Then the vertices are given by:> >  t = linspace(0,2*pi,n); % <-- You choose n>  x = a*cos(t)+x0;>  y = b*sin(t)+y0;> >   Note: The spacing along the polygon is not uniform here.  To do that would require the use of elliptic integrals.> > Roger StaffordThanks for the tip! Do you mind explaining how I could test whether a coordinate falls within an ellipse using just the equation of an ellipse and not converting it to polygon coordinates?
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