I have a complicated function that I would like to solve for the roots. The function comprises Bessel and Hankel functions:
freq = 5*^9; Omg = 2*Pi*freq; rho = 15 ; vco = 5907.5 (*core velocity*); vcl = 5944 (*clad velocity*); m = 0 ; U = Sqrt[Omg^2/vco^2 - Omg^2/v]; W = Sqrt[Omg^2/vcl^2 - Omg^2/v]; NSolve[U*BesselJ[m + 1, U*rho]*HankelH1[m, W*rho] - W*HankelH1[m + 1, W*rho]*BesselJ[m, U*rho]==0, v]
However, NSolve does not evaluate. I have also tried using FindRoot but I have no idea what starting value to give. Plotting the function (with all variables equal to 1 for simplicity) is of no help for guessing starting values.