Merged in feature/small-things (pull request #102)

* Print symbol interpretation of key in IndeterminantLinearSystemException.

gtsam/3rdparty/metis/libmetis/CMakeLists.txt

@@ -3,6 +3,7 @@ include_directories(.)
 # Find sources.
 file(GLOB metis_sources *.c)
 # Build libmetis.
+add_definitions(-fPIC)
 add_library(metis ${METIS_LIBRARY_TYPE} ${GKlib_sources} ${metis_sources})
 if(UNIX)
   target_link_libraries(metis m)

gtsam/linear/linearExceptions.cpp

@@ -17,7 +17,7 @@
  */
 
 #include <gtsam/linear/linearExceptions.h>
-
+#include <gtsam/inference/Symbol.h>
 #include <boost/format.hpp>
 
 namespace gtsam {
@@ -25,16 +25,19 @@ namespace gtsam {
   /* ************************************************************************* */
   const char* IndeterminantLinearSystemException::what() const throw()
   {
-    if(!description_)
+    if(!description_) {
       description_ = String(
           "\nIndeterminant linear system detected while working near variable\n"
-          + boost::lexical_cast<String>(j_) + ".\n"
+          + boost::lexical_cast<String>(j_) +
+          + " (Symbol: " + boost::lexical_cast<String>(
+              gtsam::DefaultKeyFormatter(gtsam::Symbol(j_))) + ").\n"
           "\n\
 Thrown when a linear system is ill-posed.  The most common cause for this\n\
 error is having underconstrained variables.  Mathematically, the system is\n\
 underdetermined.  See the GTSAM Doxygen documentation at\n\
 http://borg.cc.gatech.edu/ on gtsam::IndeterminantLinearSystemException for\n\
 more information.");
+    }
     return description_->c_str();
   }
 

gtsam/navigation/PreintegrationBase.h

@@ -83,7 +83,7 @@ public:
     integrationCovariance_(integrationErrorCovariance) {}
 
   /// methods to access class variables
-  const bool use2ndOrderIntegration() const {return use2ndOrderIntegration_;}
+  bool use2ndOrderIntegration() const {return use2ndOrderIntegration_;}
   const Vector3& deltaPij() const {return deltaPij_;}
   const Vector3& deltaVij() const {return deltaVij_;}
   const imuBias::ConstantBias& biasHat() const { return biasHat_;}