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From Juan Barandiaran <>
Subject [math] Complex Tanh for "big" numbers
Date Fri, 09 Dec 2011 07:51:55 GMT

In the tanh is computed with the following formula:

tanh(a + bi) = sinh(2a)/(cosh(2a)+cos(2b)) + [sin(2b)/(cosh(2a)+cos(2b))]i

The problem that I'm finding is that as soon as "a" is a "big" number,
both sinh(2a) and cosh(2a) are infinity and then the method tanh returns in
the real part NaN (infinity/infinity) when it should return 1.0.

Wouldn't it be appropiate to add something as in the FastMath library??:

if (real>20.0){
      return createComplex(1.0, 0.0);
if (real<-20.0){
      return createComplex(-1.0, 0.0);

Best regards,


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