Bessel Equation VPASolve for the order

Hi all,

I am trying to solve a simple equation like

syms E
eqn1 = besselk(E,3)==5

eqn1 = 

vpasolve(eqn1,E)

Error using mupadengine/feval_internal
Unable to differentiate the equation.

Error in sym/vpasolve (line 172)
sol = eng.feval_internal('symobj::vpasolve',eqns,vars,X0);

for the variable E. But the problem I encounter is "Error using mupadengine/feval_internal. Unable to differentiate the equation."

Does anyone know an alternative way to solve this using vpasolve?

Thanks.

Answer 1

[Torsten]

nu = 0:0.1:7;
B = besselk(nu,3)-5;
plot(nu,B)

fun = @(nu)besselk(nu,3)-5;
nu = fzero(fun,[6 7])

nu = 6.2691

[bil]

Hi,

Thanks for the response. I should have been more clear in my question, which I edited now. I was wondering if it was still possible to solve such an equation using vpasolve.

[Torsten]

I should have been more clear in my question, which I edited now. I was wondering if it was still possible to solve such an equation using vpasolve.

No. That's why I used fzero (or fsolve).