Orthonormal basis functions for L^2(R)

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SUMMARY

Sets of functions that form an orthonormal basis for the space of square integrable functions over the reals, L2(ℝ), include Hermite polynomials and Haar wavelets. Hermite polynomials serve as an orthogonal basis when multiplied by suitable scalars to achieve orthonormality. Additionally, Haar wavelets provide a complete orthogonal system for functions on the unit interval, which can be extended to L2(ℝ). The discussion highlights the need for further exploration of orthonormal bases with support across the entire real line, particularly focusing on rapidly decaying functions.

PREREQUISITES
  • Understanding of L2(ℝ) space and square integrable functions
  • Knowledge of Hermite polynomials and their properties
  • Familiarity with wavelet theory, specifically Haar wavelets
  • Concept of orthonormality in function spaces
NEXT STEPS
  • Research the properties and applications of Hermite polynomials in functional analysis
  • Explore the theory and applications of Haar wavelets in signal processing
  • Investigate other orthonormal bases for L2(ℝ), such as Fourier series and B-splines
  • Study rapidly decaying functions and their role in constructing orthonormal bases
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Mathematicians, physicists, and engineers interested in functional analysis, signal processing, and the study of orthonormal bases in L2(ℝ).

mnb96
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Hello,

are there sets of functions that form an orthonormal basis for the space of square integrable functions over the reals L2(ℝ)?
According to Wikipedia the hermite polynomials form an orthogonal basis (w.r.t. to a certain weight function) for L2(ℝ). So I guess it would be a matter of multiplying the polynomials by suitable scalars in order to make them orthonormal.
Are there other known examples besides the Hermite polynomials?
 
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Hi micromass!
thanks for your reply. Your answer basically answer my question.
Apparently the Haar wavelets "constitute a complete orthogonal system for the functions on the unit interval".

I was now wondering if there are more orthonormal bases for functions in L2(ℝ) whose support is the whole real line, e.g. rapidly decaying functions.
 

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