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Finding the area inside a convex hull 3

Posted by Doug Hull,

This quick video answers a question about finding the area of the smallest polygon that covers a set of points. It is a chance to use a few commands in MATLAB to simplify a script. Here is the code that will be discussed.
 x1 = rand(1,10);
 y1 = rand(1,10);

 vi = convhull(x1,y1);
 polyarea(x1(vi),y1(vi))

 plot(x1,y1,'.')
 axis equal
 hold on
 fill ( x1(vi), y1(vi), 'r','facealpha', 0.5 ); 
 hold off

3 CommentsOldest to Newest

Ali replied on : 1 of 3
Hello Doug , Thank you for this video and this code. I have a question though. What can I do in order to find the integral of a function over a general polygon? In other words, in the case of area, we know that the function we are integrating is 1, but what if I am given a general function f(x,y) that I need to find its integral over a convex polygon? Note that I am given the polygon as a set of points similar to your example. Thanks in advance.
Doug replied on : 2 of 3
@Ali, I think you will find this most instructive: https://www.mathworks.com/help/matlab/ref/integral2.html Look at doing the triangular bit.