remove unneeded delta_psi_prime

Author: yardasol

include/openmc/random_ray/random_ray.h

@@ -91,10 +91,6 @@ class RandomRay : public Particle {
   bool is_active_ {false};
   bool is_alive_ {true};
 
-  //---------------------------------------------------------------------------
-  // Private data members for kinetic simulations
-  vector<float> delta_psi_prime_;
-
 }; // class RandomRay
 
 } // namespace openmc

src/random_ray/random_ray.cpp

@@ -252,8 +252,7 @@ RandomRay::RandomRay()
   : angular_flux_(data::mg.num_energy_groups_),
     delta_psi_(data::mg.num_energy_groups_),
     negroups_(data::mg.num_energy_groups_),
-    angular_flux_prime_(data::mg.num_energy_groups_),
-    delta_psi_prime_(data::mg.num_energy_groups_)
+    angular_flux_prime_(data::mg.num_energy_groups_)
 
 {
   if (source_shape_ == RandomRaySourceShape::LINEAR ||
@@ -456,17 +455,14 @@ void RandomRay::attenuate_flux_flat_source(
         RandomRay::time_method_ == RandomRayTimeMethod::PROPAGATION) {
       float T1 = srh.T1(g);
 
-      // Source Derivative Propogation terms for Time Derivative
-      // Characteristic Equation
+      // Source Derivative Propogation terms for Characteristic Equation
       float inverse_vbar = domain_->inverse_vbar_[material * negroups_ + g];
       new_delta_psi += T1 * inverse_vbar * exponential / sigma_t;
       new_delta_psi += distance * inverse_vbar * (angular_flux_prime_[g] - T1) *
                        (1 - exponential);
 
       // Time Derivative Characteristic Equation
-      float new_delta_psi_prime = (angular_flux_prime_[g] - T1) * exponential;
-      delta_psi_prime_[g] = new_delta_psi_prime;
-      angular_flux_prime_[g] -= new_delta_psi_prime;
+      angular_flux_prime_[g] -= (angular_flux_prime_[g] - T1) * exponential;
     }
     delta_psi_[g] = new_delta_psi;
     angular_flux_[g] -= new_delta_psi;