Log2xr
Log2xr is a notation sometimes used in mathematical and computational contexts to denote the binary (base-2) logarithm of a quantity indexed by r, frequently the r-th component of a vector x. Because it is not a single universally fixed function, its exact meaning can vary with discipline, but the most common interpretation is the logarithm base 2 of x_r, or log2(x_r).
Definition and notation. If x is a vector with components x_1, x_2, ..., then log2xr is typically written
Properties. The function is monotone increasing on its domain, with a concave shape. It converts multiplicative
Calculation and handling of invalid inputs. In software and calculations, values with x_r ≤ 0 are undefined
Applications. Log2xr is used for data normalization and feature scaling, information-theoretic measures, and bit-length calculations (for
See also. Logarithm base 2, binary logarithm, log2, vector notation, componentwise operations.