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  2. Order of operations - Wikipedia

    en.wikipedia.org/wiki/Order_of_operations

    For example, multiplication is granted a higher precedence than addition, and it has been this way since the introduction of modern algebraic notation. [ 2 ] [ 3 ] Thus, in the expression 1 + 2 × 3 , the multiplication is performed before addition, and the expression has the value 1 + (2 × 3) = 7 , and not (1 + 2) × 3 = 9 .

  3. Spectral method - Wikipedia

    en.wikipedia.org/wiki/Spectral_method

    Compute the Fourier transform (b j,k) of g.Compute the Fourier transform (a j,k) of f via the formula ().Compute f by taking an inverse Fourier transform of (a j,k).; Since we're only interested in a finite window of frequencies (of size n, say) this can be done using a fast Fourier transform algorithm.

  4. Endogeneity (econometrics) - Wikipedia

    en.wikipedia.org/wiki/Endogeneity_(econometrics)

    The endogeneity problem is particularly relevant in the context of time series analysis of causal processes. It is common for some factors within a causal system to be dependent for their value in period t on the values of other factors in the causal system in period t − 1. Suppose that the level of pest infestation is independent of all ...

  5. Finite difference method - Wikipedia

    en.wikipedia.org/wiki/Finite_difference_method

    For example, consider the ordinary differential equation ′ = + The Euler method for solving this equation uses the finite difference quotient (+) ′ to approximate the differential equation by first substituting it for u'(x) then applying a little algebra (multiplying both sides by h, and then adding u(x) to both sides) to get (+) + (() +).

  6. Godunov's scheme - Wikipedia

    en.wikipedia.org/wiki/Godunov's_scheme

    Obtain the solution for the local Riemann problem at the cell interfaces. This is the only physical step of the whole procedure. The discontinuities at the interfaces are resolved in a superposition of waves satisfying locally the conservation equations. The original Godunov method is based upon the exact solution of the Riemann problems.

  7. Approximation algorithm - Wikipedia

    en.wikipedia.org/wiki/Approximation_algorithm

    For example, one of the long-standing open questions in computer science is to determine whether there is an algorithm that outperforms the 2-approximation for the Steiner Forest problem by Agrawal et al. [3] The desire to understand hard optimization problems from the perspective of approximability is motivated by the discovery of surprising ...

  8. Exchangeable random variables - Wikipedia

    en.wikipedia.org/wiki/Exchangeable_random_variables

    In statistics, an exchangeable sequence of random variables (also sometimes interchangeable) [1] is a sequence X 1, X 2, X 3, ... (which may be finitely or infinitely long) whose joint probability distribution does not change when the positions in the sequence in which finitely many of them appear are altered.

  9. List of PSPACE-complete problems - Wikipedia

    en.wikipedia.org/wiki/List_of_PSPACE-complete...

    Equivalence problem for star-free regular expressions with squaring. [21] Covering for linear grammars [37] Structural equivalence for linear grammars [38] Equivalence problem for Regular grammars [39] Emptiness problem for ET0L grammars [40] Word problem for ET0L grammars [41] Tree transducer language membership problem for top down finite ...