Janek Kozicki wrote:
John Maddock said: (by the date of Wed, 4 Oct 2006 18:43:00 +0100)
Mathematical Special Functions
how about sigmoid, double sigmoid and their derivatives? Used for neural networks.
Those are new ones to me.
Just a suggestion. They are so simple, that perhaps you can assume that the user can write them himself (as it was done in the past).
Unless you know some optimized way to implement them....
I suspect you will never improve on a call to exp() ? Of course if you want 1 - sigmoid(x) then you can rearrange things to avoid cancellation error. But I don't know how important such things are. One of the problems we have is that there are a virtually unlimited number of special functions, not least all those in TR1. So it's a case of trying to draw the line in the right place, but do feel free to lobby for your favorites :-) John.