atanh arc-hyperbolic tangent function missing in MS Visual C++

c++, math

Solution

Here is what is and what is not included in the various versions of the maths libraries.

Function  POSIX  old ISO  ISO C99  Microsoft(2008)  
acos      Y      Y        Y        Y     
acosh     Y      N        Y        N    
asin      Y      Y        Y        Y     
asinh     Y      N        Y        N    
atan      Y      Y        Y        Y     
atan2     Y      Y        Y        Y     
atanh     Y      N        Y        N

Can you not implement your own functions using the formulae:

    asinh(x) = log(x + sqrt(x2 + 1))
    acosh(x) = log(x + sqrt(x2 - 1))
    atanh(x) = (log(1+x) - log(1-x))/2

e.g.

float atanh (float x)
{
   //implements: return (log(1+x) - log(1-x))/2
}

Problem

I am working with some code that was previously compiled on Linux with gcc compiler, and when compiling it with MS Visual C++ 2008 the math.h doesn't appear to include all the same functionality, specifically the (inverse) arc-hyperbolic tangent atanh function. I've tried including math.h, cmath, using std::atanh, and didn't find much else with a google/MSDN search. Is there a simple header file available that I can include that has this? error C3861: 'atanh': identifier not found

Original source