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  2. Data Analysis Expressions - Wikipedia

    en.wikipedia.org/wiki/Data_Analysis_eXpressions

    Data Analysis Expressions (DAX) is the native formula and query language for Microsoft PowerPivot, Power BI Desktop and SQL Server Analysis Services (SSAS) Tabular models. DAX includes some of the functions that are used in Excel formulas with additional functions that are designed to work with relational data and perform dynamic aggregation .

  3. Frequency domain decomposition - Wikipedia

    en.wikipedia.org/wiki/Frequency_domain_decomposition

    Do a singular value decomposition of the power spectral density, i.e. ^ = where = [,,...,] is a unitary matrix holding the singular vectors, is the diagonal matrix holding the singular values . For an n {\displaystyle n} degree of freedom system, then pick the n {\displaystyle n} dominating peaks in the power spectral density using whichever ...

  4. Power Query - Wikipedia

    en.wikipedia.org/wiki/Power_Query

    Power Query was first announced in 2011 under the codename "Data Explorer" as part of Azure SQL Labs. In 2013, in order to expand on the self-service business intelligence capabilities of Microsoft Excel, the project was redesigned to be packaged as an add-in Excel and was renamed "Data Explorer Preview for Excel", [4] and was made available for Excel 2010 and Excel 2013. [5]

  5. Singular value decomposition - Wikipedia

    en.wikipedia.org/wiki/Singular_value_decomposition

    Top: The action of M, indicated by its effect on the unit disc D and the two canonical unit vectors e 1 and e 2. Left: The action of V ⁎, a rotation, on D, e 1, and e 2. Bottom: The action of Σ, a scaling by the singular values σ 1 horizontally and σ 2 vertically.

  6. Circulant matrix - Wikipedia

    en.wikipedia.org/wiki/Circulant_matrix

    An circulant matrix takes the form = [] or the transpose of this form (by choice of notation). If each is a square matrix, then the matrix is called a block-circulant matrix.. A circulant matrix is fully specified by one vector, , which appears as the first column (or row) of .

  7. Fisher information - Wikipedia

    en.wikipedia.org/wiki/Fisher_information

    If is sharply peaked with respect to changes in , it is easy to indicate the "correct" value of from the data, or equivalently, that the data provides a lot of information about the parameter . If f {\displaystyle f} is flat and spread-out, then it would take many samples of X {\displaystyle X} to estimate the actual "true" value of θ ...

  8. MultiDimensional eXpressions - Wikipedia

    en.wikipedia.org/wiki/MultiDimensional_eXpressions

    Multidimensional Expressions (MDX) is a query language for online analytical processing (OLAP) using a database management system. Much like SQL , it is a query language for OLAP cubes . [ 1 ] It is also a calculation language, with syntax similar to spreadsheet formulae.

  9. Singular spectrum analysis - Wikipedia

    en.wikipedia.org/wiki/Singular_spectrum_analysis

    The origins of SSA and, more generally, of subspace-based methods for signal processing, go back to the eighteenth century (Prony's method).A key development was the formulation of the spectral decomposition of the covariance operator of stochastic processes by Kari Karhunen and Michel Loève in the late 1940s (Loève, 1945; Karhunen, 1947).