substitution tensor

The simplest interpretation of the Kronecker delta is as the discrete version of the delta function defined by δ_(i j) congruent {0 | for i!=j 1 | for i = j. auto right match The Kronecker delta is implemented in the Wolfram Language as KroneckerDelta[i, j], as well as in a generalized form KroneckerDelta[i, j, ...] that returns 1 iff all arguments are equal and 0 otherwise. It has the contour integral representation δ_(m n) = 1/(2π i) ∮_γ z^(m - n - 1) d z, where γ is a contour corresponding to the unit circle and m and n are integers.

delta function | permutation symbol | permutation tensor