MATLAB: Undefined Function or Variable but the variable is in fact Defined

MATLABundefined variable

So clearly k is defined, but Matlab keeps telling me it is not defined. What is going on?
>> k=1
       k =
           1
  >> f_n
        f_n = 
           @(r,n)sqrt(pi/(2*k*r))*besseli(n+.5,k*r)
    >> f_n(1,1)
             Undefined function or variable 'k'.
           Error in @(r,n)sqrt(pi/(2*k*r))*besseli(n+.5,k*r)

Best Answer

The function was defined before k. When the anonymous function is created, it grabs a static snapshot of the workspace and does not update. To incorporate k, just rerun the command to create the function handle.
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