From acfe742c29a91e89f6882713f62cc4df32e32263 Mon Sep 17 00:00:00 2001
From: Alex Cunningham <alexgcunningham@gmail.com>
Date: Fri, 20 Nov 2009 05:10:55 +0000
Subject: [PATCH] Added a simple scaling function for VectorConfigs

---
 cpp/VectorConfig.cpp     | 10 ++++++++++
 cpp/VectorConfig.h       |  3 +++
 cpp/testVectorConfig.cpp | 15 +++++++++++++++
 3 files changed, 28 insertions(+)

diff --git a/cpp/VectorConfig.cpp b/cpp/VectorConfig.cpp
index 4e25e4557..619f17cb1 100644
--- a/cpp/VectorConfig.cpp
+++ b/cpp/VectorConfig.cpp
@@ -26,6 +26,16 @@ void check_size(const string& key, const Vector & vj, const Vector & dj) {
   }
 }
 
+/* ************************************************************************* */
+VectorConfig VectorConfig::scale(double gain) {
+	VectorConfig scaled;
+	string key; Vector val;
+	FOREACH_PAIR(key, val, values) {
+		scaled.insert(key, gain*val);
+	}
+	return scaled;
+}
+
 /* ************************************************************************* */
 VectorConfig VectorConfig::exmap(const VectorConfig & delta) const
 {
diff --git a/cpp/VectorConfig.h b/cpp/VectorConfig.h
index f6f744d08..4f7cb7d96 100644
--- a/cpp/VectorConfig.h
+++ b/cpp/VectorConfig.h
@@ -52,6 +52,9 @@ namespace gtsam {
      * For VectorConfig, this is just addition.
      */
     VectorConfig exmap(const VectorConfig & delta) const;
+
+    /** Scales the configuration by a gain */
+    VectorConfig scale(double gain);
  
     const_iterator begin() const {return values.begin();}
     const_iterator end()   const {return values.end();}
diff --git a/cpp/testVectorConfig.cpp b/cpp/testVectorConfig.cpp
index d5076f38f..e2e012226 100644
--- a/cpp/testVectorConfig.cpp
+++ b/cpp/testVectorConfig.cpp
@@ -88,6 +88,21 @@ TEST( VectorConfig, plus)
   CHECK(actual.equals(expected));
 }
 
+/* ************************************************************************* */
+TEST( VectorConfig, scale) {
+	VectorConfig cfg;
+	cfg.insert("x", Vector_(2, 1.0, 2.0));
+	cfg.insert("y", Vector_(2,-1.0,-2.0));
+
+	VectorConfig actual = cfg.scale(2.0);
+
+	VectorConfig expected;
+	expected.insert("x", Vector_(2, 2.0, 4.0));
+	expected.insert("y", Vector_(2,-2.0,-4.0));
+
+	CHECK(assert_equal(actual, expected));
+}
+
 /* ************************************************************************* */
 #ifdef HAVE_BOOST_SERIALIZATION
 TEST( VectorConfig, serialize)