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ln(r) is the standard natural logarithm of the real number r. Arg(z) is the principal value of the arg function; its value is restricted to (−π, π]. It can be computed using Arg(x + iy) = atan2(y, x). Log(z) is the principal value of the complex logarithm function and has imaginary part in the range (−π, π].
More generally, if x = b y, then y is the logarithm of x to base b, written log b x, so log 10 1000 = 3. As a single-variable function, the logarithm to base b is the inverse of exponentiation with base b. The logarithm base 10 is called the decimal or common logarithm and is commonly used in science and engineering.
A graph of the common logarithm of numbers from 0.1 to 100. In mathematics, the common logarithm (aka "standard logarithm") is the logarithm with base 10. [1] It is also known as the decadic logarithm, the decimal logarithm and the Briggsian logarithm.
The natural logarithm of x is generally written as ln x, log e x, or sometimes, if the base e is implicit, simply log x. [2] [3] Parentheses are sometimes added for clarity, giving ln(x), log e (x), or log(x). This is done particularly when the argument to the logarithm is not a single symbol, so as to prevent ambiguity.
All instances of log(x) without a subscript base should be interpreted as a natural logarithm, also commonly written as ln(x) or log e (x). In number theory , an arithmetic , arithmetical , or number-theoretic function [ 1 ] [ 2 ] is generally any function whose domain is the set of positive integers and whose range is a subset of the complex ...
The standard logistic function is the logistic function with parameters =, =, =, which yields = + = + = / / + /.In practice, due to the nature of the exponential function, it is often sufficient to compute the standard logistic function for over a small range of real numbers, such as a range contained in [−6, +6], as it quickly converges very close to its saturation values of 0 and 1.
The second Chebyshev function can be seen to be related to the first by writing it as = where k is the unique integer such that p k ≤ x and x < p k + 1.The values of k are given in OEIS: A206722.
Similarly, let b −k denote the product of b −1 with itself k times. For k = 0, the kth power is the identity: b 0 = 1. Let a also be an element of G. An integer k that solves the equation b k = a is termed a discrete logarithm (or simply logarithm, in this context) of a to the base b. One writes k = log b a.