# Quick Frobenius Question

1. Feb 10, 2009

### ductape

Hello, I was just wondering, if I have a differential equation that has two regular singular points, and I am asked for the general solution, do I need to use the Frobenius method about each point seperately? I suspect that I do I just want to clarify.
Thanks

2. Feb 13, 2009

### matematikawan

I think you have the option even not to use the Frobenius method. Can we avoid the regular point?

The Legendre's equation
(1-x2)y" - 2xy' + n(n+1)y = 0
have two regular points but we usually solve the equation about the ordinary point x=0.

3. Feb 14, 2009

### HallsofIvy

Staff Emeritus
Typically, we have to use Frobenious method at singular points only when we are given intial conditions at that singular point. It is easier to apply "y(x0)" and "y'(x0)" if our series solution is in terms of (x- x0)n.

4. Feb 17, 2009

### matematikawan

Yes it looks reasonable to used frobenius series for an initial value problem because of an infinite number of terms involve.

But what about a boundary value problem where we are given two points? y(x0) = y0 and y(x1) = y1 .

We still need to sum an infinite series.
Is this what ductape meant in the initial post? Used two separate series.