/*  scfatanh.cpp  by K.Tsuru  */
// function ID = 9120  since ver 2.18
/*****************************************
SComplex class
It returns artanh(z).
Catanh(z) = Clog{(1+z)/(1-z)}/2
= (1/i)arctan(iz). ver 2.21
When z = x(pure real),let atanh(x) = p,
  -1 < x = tanh(p) < 1 must be satisfied.
*****************************************/
#ifndef SN_H
#include "sn.h"
#endif

#if 0
SComplex Catanh(const SComplex& z) {
    if(Im(z) == 0.0) { // z = x
        if( Dabs(Re(z)) >= 1.0) z.Real().SetError(z.Real().DOMAIN_ERR, "Catanh(z) with z = x(|x| > 1.0))", 9120);
    }
    SComplex y = (ONE + z)/(ONE - z);

    return CsDiv(Clog(y), 2);
}
#else /********************************/

SComplex Catanh(const SComplex& z) {
    if(Im(z) == 0.0) {
        if( Dabs(Re(z)) >= 1.0) z.Real().SetError(z.Real().DOMAIN_ERR, "Catanh(z) with z = x(|x| > 1.0))", 9120);
    }
    return MI*Catan(IU*z); // (1/i)arctan(iz)   
}
#endif