Namespaces
Variants
Actions

Trigonometric polynomial

From Encyclopedia of Mathematics
Revision as of 08:26, 6 June 2020 by Ulf Rehmann (talk | contribs) (tex encoded by computer)
Jump to: navigation, search


finite trigonometric sum

An expression of the form

$$ T ( x) = { \frac{a _ {0} }{2} } + \sum _ {k = 1 } ^ { n } ( a _ {k} \cos kx + b _ {k} \sin kx) $$

with real coefficients $ a _ {0} , a _ {k} , b _ {k} $, $ k = 1 \dots n $; the number $ n $ is called the order of the trigonometric polynomial (provided $ | a _ {n} | + | b _ {n} | > 0 $). A trigonometric polynomial can be written in complex form:

$$ T ( x) = \sum _ {k = - n } ^ { n } c _ {k} e ^ {ikx} , $$

where

$$ 2c _ {k} = \left \{

Trigonometric polynomials are an important tool in the approximation of functions.

Comments

Cf. also Trigonometric series.

How to Cite This Entry:
Trigonometric polynomial. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Trigonometric_polynomial&oldid=11930
This article was adapted from an original article by V.I. Bityutskov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article