Re: [RT] Adaptive Caching

[Berin Loritsch]

Hunsberger, Peter wrote:

Berin Loritsch <[EMAIL PROTECTED]> asks:


Speaking of accademic, anyone have a Java implementation of 
tanh(x)?  The java.lang.Math class only has tan(x) or 
atan(x), but no hyperbolic function.


Spoke to soon, Google search digs it up: 

	http://www.bsdg.org/swag/MATH/0067.PAS.html

Yields:

 TANH := SINH(x)/COSH(x);

 SINH := (EXP(x)-EXP(-x))/2;

 COSH := (EXP(x)+EXP(-x))/2;
Ok.  Using agebraic substitution:
          sinh(x)
tanh(x) = -------
          cosh(x)
           exp(x) - exp(-x)
           ----------------
                   2
tanh(x) = ------------------
           exp(x) + exp(-x)
           ----------------
                   2
          exp(x) - exp(-x)
tanh(x) = ----------------
          exp(x) + exp(-x)
          exp(x) *( exp(x) - exp(-x) )
tanh(x) = ----------------------------
          exp(x) *( exp(x) + exp(-x) )
          exp(2x) - 1
tanh(x) = -----------
          exp(2x) + 1
I think I have it ok.

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