comment about theory and origins of trap.h

diff --git a/lib/ortho/trap.h b/lib/ortho/trap.h
index 273e6bff964bbab37f7bb2c7011e0aaa0bdefb21..da323dea722e55c708f5436bffef3cf059d296ef 100644 (file)
--- a/lib/ortho/trap.h
+++ b/lib/ortho/trap.h
@@ -1,3 +1,11 @@
+/**
+ * @file
+ * @brief trapezoid elements and utilities for partition.c
+ *
+ * See [Fast polygon triangulation based on Seidel's algorithm](http://gamma.cs.unc.edu/SEIDEL/)
+ *
+ */
+
 /*************************************************************************
  * Copyright (c) 2011 AT&T Intellectual Property 
  * All rights reserved. This program and the accompanying materials