What is index notation?
In mathematics and computer programming, Index notation is used
to specify the elements of an array of numbers. The terms "index
notation", or "indicial notation" are sometimes used to refer to
Einstein notation. The formalism of how indices are used varies
according to the subject. In particular, there are different
methods for referring to the elements of a list, a vector, or a
matrix, depending on whether one is writing a formal mathematical
paper for publication, or when one is writing a computer
program.
This is not to be confused with "index form" which is the
writing of prime factorizations using exponents.