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MathGroup Archive 1991

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Bug in Tanh[x]

  • To: mathgroup at
  • Subject: Bug in Tanh[x]
  • From: Barry Merriman <barry at>
  • Date: Wed, 27 Feb 91 19:07:15 -0800

Someone must have found this bug previously, but there is
a nasty bug in Tanh[x] (in version 1.* on a NeXT).

Just try 


to _see_ what I mean. (I always though tanh(x) was continuous :-)

Fortunately, its easy to write your own "tanh[x]":

tanh[x_] := (Exp[x] - Exp[-x])/(Exp[x] + Exp[-x])

which works fine.

NeXT 1.2 (Januuary 20, 1990) 

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