add inclination cosine

istellartech · Jun 1, 2024 · fc7ebf4 · fc7ebf4
1 parent 2817e97
commit fc7ebf4
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Showing 2 changed files with 6 additions and 3 deletions.
diff --git a/src/pybind_coordinate.cpp b/src/pybind_coordinate.cpp
@@ -31,6 +31,7 @@ PYBIND11_MODULE(coordinate_c, m) {
     m.def("angular_momentum_vec", &angular_momentum_vec, "angular momentum vector from ECI position and velocity");
     m.def("angular_momentum", &angular_momentum, "angular momentum from ECI position and velocity");
     m.def("inclination_rad", &inclination_rad, "inclination from ECI position and velocity");
+    m.def("inclination_cosine", &inclination_cosine, "inclination cosine from ECI position and velocity");
     m.def("laplace_vector", &laplace_vector, "Laplace vector from ECI position and velocity");
     m.def("orbit_energy", &orbit_energy, "orbital energy from ECI position and velocity");
     m.def("angular_momentum_from_altitude", &angular_momentum_from_altitude, "angular momentum from altitude");

diff --git a/src/wrapper_coordinate.hpp b/src/wrapper_coordinate.hpp
@@ -200,11 +200,13 @@ vec3d angular_momentum_vec(vec3d pos_eci, vec3d vel_eci) {
 double angular_momentum(vec3d pos_eci, vec3d vel_eci) {
   return angular_momentum_vec(pos_eci, vel_eci).norm();
 }
+double inclination_cosine(vec3d pos_eci, vec3d vel_eci) {
+  return angular_momentum_vec(pos_eci, vel_eci)[2] /
+         angular_momentum(pos_eci, vel_eci);
+}
 
 double inclination_rad(vec3d pos_eci, vec3d vel_eci) {
-  double ci = angular_momentum_vec(pos_eci, vel_eci)[2] /
-         angular_momentum(pos_eci, vel_eci);
-  return acos(ci);
+  return acos(inclination_cosine(pos_eci, vel_eci));
 }
 
 vec3d laplace_vector(vec3d pos_eci, vec3d vel_eci) {