Code-equations/Gravitational-Potential-including-indirect-terms.md

@@ -60,8 +60,12 @@ To select this choice for a simulation in the config file:
 ## The indirect terms 
 Two terms in the potential accounts for the acceleration of the primary they come  from the acceleration  due respectively to the planet(s) and to the disk:
 
-$`\tilde \Phi_p = {{ G m_p} \over {r_p^3}}(r_p\codot r)`$
+$`\tilde \Phi_p = {{ G m_p} \over {r_p^3}}(\vec r_p \cdot \vec r)`$
 
  
+with $`\vec r_p`$ and $`\vec r`$ indicating the distance between the
+planet and the star and a grid cell and the star
 
+$`\tilde \Phi_d =   \vec a  \cdot \vec r `$
 
+where $`\vec a$ is the acceleration of the primary due to the whole disk.
\ No newline at end of file