correct mass calculation

lib/tree.cpp

@@ -2,9 +2,9 @@
 #include "node.hpp"
 
 #include <vector>
-#include <iostream>
 
 Tree::Tree(double* masses, double* positions, double* forces, unsigned nParticles, double size, Vector center) {
+    masses_ = masses;
     positions_ = positions;
     forces_ = forces;
     nParticles_ = nParticles;
@@ -24,7 +24,7 @@ Tree::~Tree() {
     delete root_;
 }
 
-void Tree::calculateForce(unsigned particle) {
+void Tree::updateForce(unsigned particle) {
     Vector force = root_->calculateForce(particle);
     for (unsigned i=0; i < 3; ++i) forces_[3*particle + i] = force[i];
 }

lib/tree.hpp

@@ -12,8 +12,8 @@ public:
     Tree(double* masses, double* positions, double* forces_, unsigned nParticles, double size, Vector center);
     // Destructor
     ~Tree();
-    // Calculate force on a particle
-    void calculateForce(unsigned particle);
+    // Update force on a particle
+    void updateForce(unsigned particle);
     // Update tree
     void update();