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The identities of logarithms can be used to approximate large numbers. Note that log b (a) + log b (c) = log b (ac), where a, b, and c are arbitrary constants. Suppose that one wants to approximate the 44th Mersenne prime, 2 32,582,657 −1. To get the base-10 logarithm, we would multiply 32,582,657 by log 10 (2), getting 9,808,357.09543 ...
Title page of John Napier's Mirifici Logarithmorum Canonis Descriptio from 1614, the first published table of logarithms A page from Napier's Mirifici logarithmorum tables, with trigonometric and log trig data for 34 degrees. The history of logarithms is the story of a correspondence (in modern terms, a group isomorphism) between multiplication ...
For example, a 5.0 earthquake releases 32 times (10 1.5) and a 6.0 releases 1000 times (10 3) the energy of a 4.0. [61] Apparent magnitude measures the brightness of stars logarithmically. [62] In chemistry the negative of the decimal logarithm, the decimal cologarithm, is indicated by the letter p. [63]
The natural logarithm of e itself, ln e, is 1, because e 1 = e, while the natural logarithm of 1 is 0, since e 0 = 1. The natural logarithm can be defined for any positive real number a as the area under the curve y = 1/x from 1 to a [4] (with the area being negative when 0 < a < 1). The simplicity of this definition, which is matched in many ...
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 name "Briggsian logarithm" is in honor of the British mathematician Henry Briggs who conceived of and developed the values for the "common logarithm".
On the region consisting of complex numbers that are not negative real numbers or 0, the function is the analytic continuation of the natural logarithm. The values on the negative real line can be obtained as limits of values at nearby complex numbers with positive imaginary parts.
Every concave function that is nonnegative on its domain is log-concave. However, the reverse does not necessarily hold. An example is the Gaussian function f(x) = exp(−x 2 /2) which is log-concave since log f(x) = −x 2 /2 is a concave function of x. But f is not concave since the second derivative is positive for | x | > 1:
The logarithm function is not defined for zero, so log probabilities can only represent non-zero probabilities. Since the logarithm of a number in ( 0 , 1 ) {\displaystyle (0,1)} interval is negative, often the negative log probabilities are used.