Yeah, that's true. Someone at some point started using the term wrong and it stuck. Kind of like the words occlude and albedo which are also typically used incorrectly in graphics.
It is jargon, i think pretty much any field has those - though graphics and gamedev have a lot of their own (sometimes conflicting).
My favorite is "brush" to mean convex polyhedron. I remember when i joined a gamedev company years ago and was looking around the editor and noticed some buttons with a paintbrush - clicking it didn't do anything and after asking around it turned out this was for making in-editor 3d geometry but the artist who made the icon (we wanted to release the editor which meant someone went and remade all the programmer-made icons) didn't knew about it or about the terminology (i think the original programmer-made icon had the word "brush"), so he just drew what the button was supposedly about: a brush :-P.
I just went through this a couple of weeks ago. I joined a game dev company recently and I’ve been experiencing a lot of it. Another is calling everything a particle for physics simulations. Please let me know if you can think of any other.
in permutations the ordering of the individual elements is important (a different order of exactly the same elements is a different permutation), but it's irrelevant in uber shaders. they should just say combinations (different elements are toggled on and off).
With permutations without repetitions you get factorials (n!) while with permutations with repetitions you get n^n.
More precisely, when taking N objects out of M, the number of permutations is always computed by multiplying N factors, which are either all equal to M when repetitions are allowed (i.e. the power M^N) or they are decreasing by one at each factor when the extracted objects must be unique (i.e. M*(M-1)*(M-2) ...), which gives the factorial in the case of N taken out of N.
With combinations either with or without repetitions you also get a product of N factors, but each factor is much smaller, being a ratio of two integers, instead of the integer that is the numerator. This is usually written in a form that is useless for actual computation, as the ratio between a factorial and the product of other two factorials (which differ between the two kinds of combinations).
The sum of all combinations without repetitions is 2^N (when repetitions are allowed, the sum is infinite).
Nope. Combinations are subsets: you either include or exclude each element. So 2^n. With permutations, you have n options for the first element, (n-1) options for the second, and so on. Thus n! possibilities total.
