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Shark-ML / Shark

The Shark Machine Leaning Library. See more:
http://shark-ml.github.io/Shark/
GNU Lesser General Public License v3.0
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Sigmoid Kernel #255

Closed John1911603424 closed 5 years ago

John1911603424 commented 5 years ago

Hi,do you know where sigmoid kernel is? I didn't find it.

Ulfgard commented 5 years ago

We have not implemented it.

Ulfgard commented 5 years ago

a longer reply: in our personal experience, the sigmoid kernel rarely makes sense. It is slightly difficult to work with because positive-definiteness of the kernel is not guaranteed. Also as a model the sigmoid kernel has super weird behaviour.

See here:

https://cloud.githubusercontent.com/assets/5733246/18803657/6883294a-81c8-11e6-8950-6989e765966a.png

John1911603424 commented 5 years ago

Thanks.