[R] Optimize function in R: unable to find maximum of logistic function

[Rui Barradas]

Hello,

This seems like a bug, removing 'maximum = TRUE' has no effect except 
that the returned value says it's a minimum, not a maximum.

Rui Barradas

Em 28-10-2013 17:00, Shantanu MULLICK escreveu:
> Hello Everyone,
>
> I want to perform a 1-D optimization by using the optimize() function. I
> want to find the maximum value of a "logistic" function. The optimize()
> function gives the wrong result.
>
> My code:
> f= function (k) {
> T_s = 20
> result = (2- 2/(1+ exp(-2*T_s*k)))
> return(result)
> }
> optimize(f, c(0, 5), tol = 0.0000000000001, maximum= TRUE)
>
> The maximum value for the function happens at k=0, and the maximum value is
> 1. Yet  the optimise function, says that the maximum value happens at k=
> 4.9995, and the maximum value is 0.
>
> Thanks in advance!
>
> Warm Regards,
> Shantanu
>
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