A Test for the Convexity of a Quadrilateral

This Demonstration draws the quadrilateral green if convex, orange if concave, and red if reflex.


The idea is to check if the diagonals of the quadrilateral intersect as line segments. See P. Bourke, "Intersection Point of Two Lines (2 Dimensions)" and take note of the last paragraph. The formulas involve determinants; see the Wikipedia entry, "Line-Line Intersection".
comments
 
Powered by Wolfram Mathematica
Give us your feedback
Give us your feedback

Source page:




 often  occasionally  never

Note: Please do not include anything you consider confidential or proprietary. Your message and contact information may be shared with the author of any specific Demonstration for which you give feedback, but will not otherwise be published or distributed.
Privacy Policy »

Note: To run this Demonstration you need the free
Mathematica Player
or Mathematica 7+
Download or upgrade to Mathematica Player 7
I already have Mathematica Player or Mathematica 7+