From 0a3d9975f39f0e6c2c105ab73bc39f86b709c450 Mon Sep 17 00:00:00 2001
From: Duy-Nguyen Ta <thduynguyen@gmail.com>
Date: Tue, 19 Jun 2012 06:04:31 +0000
Subject: [PATCH] adding smart flags for several static noise model creation
 function

---
 gtsam/linear/NoiseModel.cpp |  6 ++++++
 gtsam/linear/NoiseModel.h   | 14 +++++++-------
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/gtsam/linear/NoiseModel.cpp b/gtsam/linear/NoiseModel.cpp
index a0901c58b..51f732db0 100644
--- a/gtsam/linear/NoiseModel.cpp
+++ b/gtsam/linear/NoiseModel.cpp
@@ -422,6 +422,12 @@ SharedDiagonal Constrained::QR(Matrix& Ab) const {
 
 /* ************************************************************************* */
 // Isotropic
+/* ************************************************************************* */
+Isotropic::shared_ptr Isotropic::Sigma(size_t dim, double sigma, bool smart)  {
+	if (smart && fabs(sigma-1.0)<1e-9) return Unit::Create(dim);
+	return shared_ptr(new Isotropic(dim, sigma));
+}
+
 /* ************************************************************************* */
 Isotropic::shared_ptr Isotropic::Variance(size_t dim, double variance, bool smart)  {
 	if (smart && fabs(variance-1.0)<1e-9) return Unit::Create(dim);
diff --git a/gtsam/linear/NoiseModel.h b/gtsam/linear/NoiseModel.h
index f7a1c351a..b1e65feff 100644
--- a/gtsam/linear/NoiseModel.h
+++ b/gtsam/linear/NoiseModel.h
@@ -112,6 +112,8 @@ namespace gtsam {
 		 * as indeed
 		 *   |y|^2 = y'*y = x'*R'*R*x
 		 * Various derived classes are available that are more efficient.
+		 * The named constructors return a shared_ptr because, when the smart flag is true,
+		 * the underlying object might be a derived class such as Diagonal.
 		 */
 		class Gaussian: public Base {
 
@@ -274,8 +276,8 @@ namespace gtsam {
 			 * A diagonal noise model created by specifying a Vector of precisions, i.e.
 			 * i.e. the diagonal of the information matrix, i.e., weights
 			 */
-			static shared_ptr Precisions(const Vector& precisions) {
-				return Variances(reciprocal(precisions));
+			static shared_ptr Precisions(const Vector& precisions, bool smart = false) {
+				return Variances(reciprocal(precisions), smart);
 			}
 
 			virtual void print(const std::string& name) const;
@@ -496,9 +498,7 @@ namespace gtsam {
 			/**
 			 * An isotropic noise model created by specifying a standard devation sigma
 			 */
-			static shared_ptr Sigma(size_t dim, double sigma) {
-				return shared_ptr(new Isotropic(dim, sigma));
-			}
+			static shared_ptr Sigma(size_t dim, double sigma, bool smart = false);
 
 			/**
 			 * An isotropic noise model created by specifying a variance = sigma^2.
@@ -509,8 +509,8 @@ namespace gtsam {
 			/**
 			 * An isotropic noise model created by specifying a precision
 			 */
-			static shared_ptr Precision(size_t dim, double precision)  {
-				return Variance(dim, 1.0/precision);
+			static shared_ptr Precision(size_t dim, double precision, bool smart = false)  {
+				return Variance(dim, 1.0/precision, smart);
 			}
 
 			virtual void print(const std::string& name) const;