Remove real type

[Andrei Alexandrescu]

On 04/24/2010 04:30 PM, strtr wrote:
> Andrei Alexandrescu Wrote:
>
>> On 04/24/2010 12:52 PM, strtr wrote:
>>> Walter Bright Wrote:
>>>
>>>> strtr wrote:
>>>>> Portability will become more important as evo algos get used
>>>>> more. Especially in combination with threshold functions.
>>>>> The computer will generate/optimize all input/intermediate
>>>>> values itself and executing the program on higher precision
>>>>> machines might give totally different outputs.
>>>>
>>>>
>>>> You've got a bad algorithm if increasing the precision breaks
>>>> it.
>>>
>>> No, I don't. All algorithms using threshold functions which have
>>> been generated using evolutionary algorithms will break by
>>> changing the precision. That is, you will need to retrain them.
>>> The point of most of these algorithms(eg. neural networks) is
>>> that you don't know what is happening in it.
>>
>> I'm not an expert in GA, but I can tell that a neural network that
>> is dependent on precision is badly broken.
> How can you tell?
>
>> Any NN's transfer function must be smooth.
> http://www.doc.ic.ac.uk/~nd/surprise_96/journal/vol4/cs11/report.html#Transfer%20Function
>
>  It wasn't for nothing I mentioned threshold functions
>
> Especially in the more complex spiking neural networks bases on
> dynamical systems, thresholds are kind of important.

Meh. You can't train using a gradient method unless the output is smooth 
(infinitely derivable).


Andrei