diff --git a/Ball.hpp b/Ball.hpp
index 7695011..52b2259 100644
--- a/Ball.hpp
+++ b/Ball.hpp
@@ -30,6 +30,7 @@ class Ball {
         double A, B, U, T; // Coefficients for the physical model.
         double v_x, v_z;
         void _compute_pos(double dt);
+        void _compute_parameters();
         void _compute_v_x(Point normal);
         void _compute_v_z(Point normal);
         void _compute_A_n();