Series solutions near an irregular singularity

In summary, an irregular singularity in a series solution is a point in a function where the series expansion breaks down and the function cannot be represented as a power series. It can be identified by examining the coefficients of the series expansion and can be handled using techniques such as Frobenius method or the method of series reversion. Unlike regular singularities, an irregular singularity cannot be removed from a function, but we can find a new series expansion that is valid near the singularity to analyze the function in that region.
  • #1
ShayanJ
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Consider a linear differential equation of the form [itex] y''+p(x)y'+q(x)y=0 [/itex] with an irregular singularity at [itex]x_0[/itex].
How can I found a series solution to it near [itex] x_0 [/itex]?

Thanks
 
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  • #2
Basic answer- you don't, there isn't one. If your differential equation has an "irregular singularity" at x0, then there is no series solution in a neighborhood of x0.
 
  • #3
Can you explain why?

Thanks
 

FAQ: Series solutions near an irregular singularity

What is an irregular singularity in a series solution?

An irregular singularity in a series solution is a point in a function where the series expansion breaks down and the function cannot be represented as a power series. This usually occurs when the function is not analytic at that point.

How can we identify an irregular singularity in a series solution?

An irregular singularity can be identified by examining the coefficients of the series expansion. If the coefficients do not follow a pattern or increase rapidly, it is likely that there is an irregular singularity present.

What is the difference between a regular and an irregular singularity?

A regular singularity is a point in a function where the series expansion is valid and the function can be represented as a power series. On the other hand, an irregular singularity is a point where the series expansion breaks down and the function cannot be represented as a power series.

How do we handle series solutions near an irregular singularity?

To handle series solutions near an irregular singularity, we can use techniques such as Frobenius method or the method of series reversion. These methods allow us to find a new series expansion that is valid near the irregular singularity.

Can an irregular singularity be removed from a function?

No, an irregular singularity cannot be removed from a function. It is a fundamental property of the function and cannot be altered. However, we can use techniques to find a new series expansion that is valid near the irregular singularity, making it easier to analyze the function in that region.

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