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From: krishna@aecom.YU.EDU (Krishna Ambati)
Newsgroups: sci.electronics,comp.ai,comp.ai.neural-nets
Subject: Sigmoid transfer function
Message-ID: <1945@aecom.YU.EDU>
Date: 4 Aug 88 20:28:13 GMT
Organization: Albert Einstein College of Medicine, NY
Lines: 21


I am looking for a "black box" circuit that has the product transfer
function:

Output voltage = 0.5 ( 1 + tanh ( Input voltage / "Gain" ) )

	       = 1 / ( 1 + exp ( -2 * Input voltage / "Gain" ) )

When plotted, this function looks like an elongated S

When IV = - infinity, OV = 0
When IV = + infinity, OV = 1
When IV = 0         , OV = 0.5

By the way, this question arose in connection with a neural network
problem.

Thanks.

Krishna Ambati
krishna@aecom.uucp