# Approximation theory/Related Articles

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*See also changes related to Approximation theory, or pages that link to Approximation theory or to this page or whose text contains "Approximation theory".*

## Parent topics

- Functional analysis [r]:
*Add brief definition or description* - Numerical analysis [r]: The study of finding or approximating solutions to mathematical problems using computers.
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## Subtopics

- Chebyshev approximation [r]:
*Add brief definition or description* - Least squares [r]: Method of determining the curve that best describes the relationship between expected and observed sets of data by minimizing the sums of the squares of deviation between observed and expected values.
^{[e]} - Padé approximation [r]:
*Add brief definition or description* - Trigonometric approximation [r]:
*Add brief definition or description* - Weierstrass' theorem [r]:
*Add brief definition or description* - Interpolation [r]:
*Add brief definition or description* - Splines [r]:
*Add brief definition or description*

- Approximation [r]:
*Add brief definition or description* - Function approximation [r]: Selectable function among a well-defined class that closely matches ('approximates') a target function in a task-specific way.
^{[e]} - Taylor series [r]: Representation of a function as an infinite sum of terms calculated from the values of its derivatives at a single point.
^{[e]} - Fourier series [r]: Infinite series whose terms are constants multiplied by sine and cosine functions and that can approximate a wide variety of periodic functions.
^{[e]} - Orthogonal projection [r]:
*Add brief definition or description*