Apply a Function to an Operator
     
    
    
    Arguments
    - object
- a representation of the operator. 
- ...
- further arguments passed to or from other methods. 
 
    
    Value
    
The resulting operator from the application of the function.
     
    
    
    Examples
    s <- spectral(rbind(c(0.5, 0.3), c(0.3,0.7)))
act_eigfun(s, function(x) x^2) #-> act_eigfun.spectral(...)
#>      [,1] [,2]
#> [1,] 0.34 0.36
#> [2,] 0.36 0.58