Basis function








In mathematics, a basis function is an element of a particular basis for a function space. Every continuous function in the function space can be represented as a linear combination of basis functions, just as every vector in a vector space can be represented as a linear combination of basis vectors.


In numerical analysis and approximation theory, basis functions are also called blending functions, because of their use in interpolation: In this application, a mixture of the basis functions provides an interpolating function (with the "blend" depending on the evaluation of the basis functions at the data points).




Contents






  • 1 Examples


    • 1.1 Polynomial bases


    • 1.2 Fourier basis




  • 2 References


  • 3 See also


  • 4 References





Examples



Polynomial bases


The base of a polynomial is the factored polynomial equation into a linear function.[1]



Fourier basis


Sines and cosines form an (orthonormal) Schauder basis for square-integrable functions. As a particular example, the collection:


{2sin⁡(2πnx)|n∈N}∪{2cos⁡(2πnx)|n∈N}∪{1}{displaystyle {{sqrt {2}}sin(2pi nx);|;nin mathbb {N} }cup {{sqrt {2}}cos(2pi nx);|;nin mathbb {N} }cup {1}}{{sqrt {2}}sin(2pi nx);|;nin mathbb {N} }cup {{sqrt {2}}cos(2pi nx);|;nin mathbb {N} }cup {1}

forms a basis for L2(0,1).



References



  • Ito, Kiyoshi (1993). Encyclopedic Dictionary of Mathematics (2nd ed.). MIT Press. p. 1141. ISBN 0-262-59020-4..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output .citation q{quotes:"""""""'""'"}.mw-parser-output .citation .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-limited a,.mw-parser-output .citation .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .citation .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-ws-icon a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/4/4c/Wikisource-logo.svg/12px-Wikisource-logo.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-maint{display:none;color:#33aa33;margin-left:0.3em}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}


See also












References




  1. ^ "Solutions of differential equations in a Bernstein polynomial basis". Journal of Computational and Applied Mathematics. 205 (1): 272–280. 2007-08-01. doi:10.1016/j.cam.2006.05.002. ISSN 0377-0427.








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