Inverse hyperbolic tangent.
(Quaternion overloading of standard MATLAB® function)
Y = atanh(X)
atanh(X) computes the inverse hyperbolic sine of its argument, which must be a real quaternion (atanh is not yet implemented for complexified quaternions).
This function is computed using the Matlab® function of the same name by first computing an isomorphic complex number. The result is then assigned the same quaternion axis as the original argument.
>> atanh(qi + qj + qk) ans = 0 + 0.6046 * I + 0.6046 * J + 0.6046 * K