Why do some methods take out parameters instead of returning values?

[markonius]

Some methods, such as Box.ComputeInertia and Bodies.GetDescription take an out parameter instead of returning a value. Why is that?

[RossNordby]

Historically, large struct copy avoidance, occasionally other usability considerations depending on the function.

ComputeInertia is one API in particular that tends to be very annoying as a result. Modern runtimes have significantly improved the costs involved with the direct return, too. It's something I've been intending to poke at.