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For example, the number 144 in base 10 is a sum-product number, because + + =, =, and =. A natural number n {\displaystyle n} is a sociable sum-product number if it is a periodic point for F b {\displaystyle F_{b}} , where F b p ( n ) = n {\displaystyle F_{b}^{p}(n)=n} for a positive integer p {\displaystyle p} , and forms a cycle of period p ...
For example, given 100 binary variables, …,, computing a single marginal using and the above formula would involve summing over possible values for ′. If it is known that the probability mass function p {\displaystyle p} factors in a convenient way, belief propagation allows the marginals to be computed much more efficiently.
The modified Dietz method [1] [2] [3] is a measure of the ex post (i.e. historical) performance of an investment portfolio in the presence of external flows. (External flows are movements of value such as transfers of cash, securities or other instruments in or out of the portfolio, with no equal simultaneous movement of value in the opposite direction, and which are not income from the ...
The function is tacitly assumed to be real-valued: (,, …,). Factor graphs can be combined with message passing algorithms to efficiently compute certain characteristics of the function (,, …,), such as the marginal distributions.
Riemann's original use of the explicit formula was to give an exact formula for the number of primes less than a given number. To do this, take F(log(y)) to be y 1/2 /log(y) for 0 ≤ y ≤ x and 0 elsewhere. Then the main term of the sum on the right is the number of primes less than x.
Rather, the above product representation of ζ(z) converges precisely for Re(z) > 1, where it is an analytic function. By techniques of analytic continuation, this function can be extended uniquely to an analytic function (still denoted ζ(z)) on the whole complex plane except at the point z = 1, where it has a simple pole.
For example, if one starts with Euler's totient function φ, and repeatedly applies the transformation process, one obtains: φ the totient function; φ ∗ 1 = I, where I(n) = n is the identity function; I ∗ 1 = σ 1 = σ, the divisor function; If the starting function is the Möbius function itself, the list of functions is: μ, the Möbius ...
This indicator can be used to describe the predictive accuracy of other models as long as there is observed data to compare the model results to. For example, Nash–Sutcliffe efficiency has been reported in scientific literature for model simulations of discharge; water quality constituents such as sediment, nitrogen, and phosphorus loading. [5]