try to fix unresolved external symbol error

and dividing by zero problem

Author: talregev

gtsam/geometry/SO3.cpp

@@ -388,7 +388,7 @@ Vector3 SO3::ChartAtOrigin::Local(const SO3& R, ChartJacobian H) {
 //******************************************************************************
 template <>
 GTSAM_EXPORT
-Vector9 SO3::vec(OptionalJacobian<9, 3> H) const {
+Vector9 SO<3>::vec(OptionalJacobian<9, 3> H) const {
   const Matrix3& R = matrix_;
   if (H) {
     H->setZero();

gtsam/geometry/SO3.h

@@ -97,7 +97,7 @@ Vector3 SO3::ChartAtOrigin::Local(const SO3& R, ChartJacobian H);
 
 template <>
 GTSAM_EXPORT
-Vector9 SO3::vec(OptionalJacobian<9, 3> H) const;
+Vector9 SO<3>::vec(OptionalJacobian<9, 3> H) const;
 
 #if GTSAM_ENABLE_BOOST_SERIALIZATION
 template <class Archive>

gtsam/linear/NoiseModel.h

@@ -575,6 +575,9 @@ namespace gtsam {
        * An isotropic noise model created by specifying a precision
        */
       static shared_ptr Precision(size_t dim, double precision, bool smart = true)  {
+        if (0 == precision) {
+          return nullptr;
+        }
         return Variance(dim, 1.0/precision, smart);
       }