the following lua code does not make sense

Question

I have the following bit of lua code. I am not sure what it is doing

width = aspectRatio > 1.5 and 320 or math.ceil( 480 / aspectRatio )

is it a short circuit?

Answer 1

It is indeed a short circuit. It's equivalence in c would be:

width = aspectRatio > 1.5 ? 320 : math.ceil( 480 / aspectRatio )

Or in english: if the aspect ratio is greater than 1.5, set the width to 320, otherwise set the width to the smallest integral value that is greater than or equal to the division of 480 and the aspect ratio.

Reference

http://www.lua.org/pil/3.3.html