Sledge: eh? Inertia is being modelled here.
pdx and pdy are components of the velocity vector of the ship. px and py are the position. Presumably, the d stands for delta, which I believe is mostly correct. Personally, I would have named them pvx and pvy.
pds would be better named pa, as it's the acceleration the ship undergoes when thrust is applied, but the code is fine. Unless the ship is going to be retrofitted with a different engine than the Asteroids factory default, there's no need to replace the constant with a variable.
pdx and pdy are components of the velocity vector of the ship. px and py are the position. Presumably, the d stands for delta, which I believe is mostly correct. Personally, I would have named them pvx and pvy.
pds would be better named pa, as it's the acceleration the ship undergoes when thrust is applied, but the code is fine. Unless the ship is going to be retrofitted with a different engine than the Asteroids factory default, there's no need to replace the constant with a variable.