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Fuchs' theorem: Difference between revisions

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Given a second order differential equation of the form
Given a second order differential equation of the form


<math>y'' + p(x)y'+q(x)y=g(x)</math>
:<math>y'' + p(x)y'+q(x)y=g(x)</math>


where <math>p(x)</math>, <math>q(x)</math> and <math>g(x)</math> has power series expansions at <math>x=a</math>. A solution to this second order differential equation can be expressed as a power series at <math>a</math>. Thus any solution can be written as
where <math>p(x)</math>, <math>q(x)</math> and <math>g(x)</math> has power series expansions at <math>x=a</math>. A solution to this second order differential equation can be expressed as a power series at <math>a</math>. Thus any solution can be written as


<math> y = \sum_{n=0}^\infty a_n (x-a)^n </math>,
:<math> y = \sum_{n=0}^\infty a_n (x-a)^n </math>,


where it's radius of convergence is at least as large as the minimum of the radii of convergence of <math>p(x)</math>, <math>q(x)</math> and <math>g(x)</math>.
where it's radius of convergence is at least as large as the minimum of the radii of convergence of <math>p(x)</math>, <math>q(x)</math> and <math>g(x)</math>.

Revision as of 12:00, 19 October 2008

Given a second order differential equation of the form

where , and has power series expansions at . A solution to this second order differential equation can be expressed as a power series at . Thus any solution can be written as

,

where it's radius of convergence is at least as large as the minimum of the radii of convergence of , and .

References

  • Asmar, Nakhlé H., "Partial differential equations with Fourier series and boundary value problems", ISBN: 0131480960