From 41735ff9d76fa06b258d671cf36b590e6c9e9c8e Mon Sep 17 00:00:00 2001
From: Frank Dellaert <dellaert@gmail.com>
Date: Thu, 1 Jul 2010 19:57:20 +0000
Subject: [PATCH] Added some comments with Alex

---
 cpp/LieConfig-inl.h | 20 +++++++++-----------
 cpp/LieConfig.h     | 17 +++++++++++++----
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/cpp/LieConfig-inl.h b/cpp/LieConfig-inl.h
index 6bea2d98b..2398d0762 100644
--- a/cpp/LieConfig-inl.h
+++ b/cpp/LieConfig-inl.h
@@ -2,7 +2,7 @@
  * LieConfig.cpp
  *
  *  Created on: Jan 8, 2010
- *      Author: richard
+ *  @Author: Richard Roberts
  */
 
 #pragma once
@@ -57,8 +57,7 @@ namespace gtsam {
   template<class J, class T>
   size_t LieConfig<J,T>::dim() const {
   	size_t n = 0;
-  	typedef pair<J,T> Value;
-  	BOOST_FOREACH(const Value& value, values_)
+  	BOOST_FOREACH(const typename Values::value_type& value, values_)
   		n += gtsam::dim(value.second);
   	return n;
   }
@@ -66,8 +65,7 @@ namespace gtsam {
   template<class J, class T>
   VectorConfig LieConfig<J,T>::zero() const {
   	VectorConfig z;
-  	typedef pair<J,T> Value;
-  	BOOST_FOREACH(const Value& value, values_)
+  	BOOST_FOREACH(const typename Values::value_type& value, values_)
   		z.insert(value.first,gtsam::zero(gtsam::dim(value.second)));
   	return z;
   }
@@ -122,8 +120,8 @@ namespace gtsam {
   template<class J, class T>
   LieConfig<J,T> expmap(const LieConfig<J,T>& c, const VectorConfig& delta) {
 		LieConfig<J,T> newConfig;
-		typedef pair<J,T> Value;
-		BOOST_FOREACH(const Value& value, c) {
+		typedef pair<J,T> KeyValue;
+		BOOST_FOREACH(const KeyValue& value, c) {
 			const J& j = value.first;
 			const T& pj = value.second;
 			Symbol jkey = (Symbol)j;
@@ -145,8 +143,8 @@ namespace gtsam {
     }
     LieConfig<J,T> newConfig;
     int delta_offset = 0;
-		typedef pair<J,T> Value;
-		BOOST_FOREACH(const Value& value, c) {
+		typedef pair<J,T> KeyValue;
+		BOOST_FOREACH(const KeyValue& value, c) {
 			const J& j = value.first;
 			const T& pj = value.second;
       int cur_dim = dim(pj);
@@ -161,8 +159,8 @@ namespace gtsam {
   template<class J, class T>
   VectorConfig logmap(const LieConfig<J,T>& c0, const LieConfig<J,T>& cp) {
   	VectorConfig delta;
-  	typedef pair<J,T> Value;
-  	BOOST_FOREACH(const Value& value, cp) {
+		typedef pair<J,T> KeyValue;
+  	BOOST_FOREACH(const KeyValue& value, cp) {
   		if(c0.exists(value.first))
   			delta.insert(value.first,
   					logmap(c0[value.first], value.second));
diff --git a/cpp/LieConfig.h b/cpp/LieConfig.h
index acc9bdde7..69a3bbde3 100644
--- a/cpp/LieConfig.h
+++ b/cpp/LieConfig.h
@@ -2,9 +2,15 @@
  * LieConfig.h
  *
  *  Created on: Jan 5, 2010
- *      Author: Richard Roberts
+ *  @Author: Richard Roberts
  *
  *  A templated config for Lie-group elements
+ *
+ *  Detailed story:
+ *  A configuration is a map from keys to values. It is used to specify the value of a bunch
+ *  of variables in a factor graph. A LieConfig is a configuration which can hold variables that
+ *  are elements of Lie groups, not just vectors. It then, as a whole, implements a aggregate type
+ *  which is also a Lie group, and hence supports operations dim, exmap, and logmap.
  */
 
 #pragma once
@@ -25,17 +31,20 @@ namespace gtsam {
 
 	/**
 	 * Lie type configuration
+	 * Takes two template types
+	 *  J: a type to look up values in the configuration (need to be sortable)
+	 *  T: the type of values being stored in the configuration
 	 */
   template<class J, class T>
-  class LieConfig : public Testable<LieConfig<J,T> > {
+  class LieConfig : public Testable<LieConfig<J, T> > {
 
   public:
 
     /**
      * Typedefs
      */
-    typedef J Key;
-    typedef T Value;
+  	typedef J Key;
+  	typedef T Value;
     typedef std::map<J, T> Values;
     typedef typename Values::iterator iterator;
     typedef typename Values::const_iterator const_iterator;