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  2. Natural logarithm - Wikipedia

    en.wikipedia.org/wiki/Natural_logarithm

    The natural logarithm of a number is its logarithm to the base of the mathematical constant e, which is an irrational and transcendental number approximately equal to 2.718 281 828 459. 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 .

  3. Logarithm of a matrix - Wikipedia

    en.wikipedia.org/wiki/Logarithm_of_a_matrix

    Definition. The exponential of a matrix A is defined by =!. Given a matrix B, another matrix A is said to be a matrix logarithm of B if e A = B.. Because the exponential function is not bijective for complex numbers (e.g. = =), numbers can have multiple complex logarithms, and as a consequence of this, some matrices may have more than one logarithm, as explained below.

  4. Stirling's approximation - Wikipedia

    en.wikipedia.org/wiki/Stirling's_approximation

    Comparison of Stirling's approximation with the factorial. In mathematics, Stirling's approximation (or Stirling's formula) is an asymptotic approximation for factorials. It is a good approximation, leading to accurate results even for small values of . It is named after James Stirling, though a related but less precise result was first stated ...

  5. Binary logarithm - Wikipedia

    en.wikipedia.org/wiki/Binary_logarithm

    Binary logarithm. Graph of x as a function of a positive real number x. In mathematics, the binary logarithm ( log2 n) is the power to which the number 2 must be raised to obtain the value n. That is, for any real number x , For example, the binary logarithm of 1 is 0, the binary logarithm of 2 is 1, the binary logarithm of 4 is 2, and the ...

  6. Prime number theorem - Wikipedia

    en.wikipedia.org/wiki/Prime_number_theorem

    All instances of log ( x) without a subscript base should be interpreted as a natural logarithm, commonly notated as ln ( x) or log e ( x ). In mathematics, the prime number theorem ( PNT) describes the asymptotic distribution of the prime numbers among the positive integers. It formalizes the intuitive idea that primes become less common as ...

  7. Logarithm - Wikipedia

    en.wikipedia.org/wiki/Logarithm

    In mathematics, the logarithm is the inverse function to exponentiation. That means that the logarithm of a number x to the base b is the exponent to which b must be raised to produce x. For example, since 1000 = 103, the logarithm base of 1000 is 3, or log10 (1000) = 3.

  8. Logarithmic decrement - Wikipedia

    en.wikipedia.org/wiki/Logarithmic_decrement

    The logarithmic decrement is defined as the natural log of the ratio of the amplitudes of any two successive peaks: where x ( t) is the overshoot (amplitude - final value) at time t and x(t + nT) is the overshoot of the peak n periods away, where n is any integer number of successive, positive peaks. The damping ratio is then found from the ...

  9. Entropy (information theory) - Wikipedia

    en.wikipedia.org/wiki/Entropy_(information_theory)

    t. e. In information theory, the entropy of a random variable is the average level of "information", "surprise", or "uncertainty" inherent to the variable's possible outcomes. Given a discrete random variable , which takes values in the set and is distributed according to , the entropy is. where denotes the sum over the variable's possible values.