comparison toolboxes/FullBNT-1.0.7/KPMtools/polygon_area.m @ 0:e9a9cd732c1e tip

first hg version after svn

+function  a = polygon_area(x,y)
+% AREA  Area of a planar polygon.
+%	AREA(X,Y) Calculates the area of a 2-dimensional
+%	polygon formed by vertices with coordinate vectors
+%	X and Y. The result is direction-sensitive: the
+%	area is positive if the bounding contour is counter-
+%	clockwise and negative if it is clockwise.
+%
+%	See also TRAPZ.
+
+%  Copyright (c) 1995 by Kirill K. Pankratov,
+%	[e-mail].
+%	04/20/94, 05/20/95  
+
+ % Make polygon closed .............
+x = [x(:); x(1)];
+y = [y(:); y(1)];
+
+ % Calculate contour integral Int -y*dx  (same as Int x*dy).
+lx = length(x);
+a = -(x(2:lx)-x(1:lx-1))'*(y(1:lx-1)+y(2:lx))/2;
+a = abs(a);