It depends. x and y are either elements or coordinates, a and b usually elements though in e.g. Haskell reserved (by convention) for type variables.
The ijkl series is reserved for indices. nm etc. are the counts of something, as such you’ll see i counting up to n. Both are due to mathematical sum notation and general mathematical convention. Random google result:
Let x1, x2, x3, …xn denote a set of n numbers. x1 is the first number in the set. xi represents the ith number in the set.
…if you’re using a language in which you use i often chances are you should stop coding in C and get yourself a language with iterators. Manual loops are a bug magnet.
It depends.
xandyare either elements or coordinates,aandbusually elements though in e.g. Haskell reserved (by convention) for type variables.The
ijklseries is reserved for indices.nmetc. are the counts of something, as such you’ll seeicounting up ton. Both are due to mathematical sum notation and general mathematical convention. Random google result:…if you’re using a language in which you use
ioften chances are you should stop coding in C and get yourself a language with iterators. Manual loops are a bug magnet.