Find a Frobenius Approximation (AsymptoticDSolveValue)
A linear ordinary differential equation can be approximated by a Frobenius series 
near a regular singular point 
for the equation. This example shows how to obtain such an approximation using AsymptoticDSolveValue.
Solve Bessel's equation of order 
around the regular singular point 
.
Plot the two components of the general solution. One branch of the solution in this case exhibits a singular behavior near the origin.
The Frobenius solution may include logarithmic terms, as illustrated in the following.
The asymptotic approximation happens to be an exact solution in this case.
