No ATANH?

[hcrisp]

There is a TAN and a ATAN. There is a TANH. But is there no inverse hyperbolic tangent function, such as ATANH?

[hcrisp]

I guess you can make your own.


FUNCTION ATANH, arg
RETURN, 0.5 * ALOG((1. + arg)/(1. - arg))
END

[acg]

There is no ATANH function in PV-WAVE. However, you can easily create your own routines:


FUNCTION atanh, x
RETURN, 0.5*ALOG((1+x) / (1-x))
END

FUNCTION asinh, x
RETURN, ALOG(x + SQRT(x*x+1))
END

FUNCTION acosh, x
RETURN, ALOG(x + SQRT(x*x-1))
END

[omega]

Portions of the domain may warrant special consideration. For possible guidance, see the comment header of the FDLIBM implementation of atanh: http://www.netlib.org/fdlibm/e_atanh.c.