/*  scfclog.cpp  by K.Tsuru  */
// function ID = 9108
/*************************************************
SComplex class log(z)
Let z = x+i*y = |z|*exp{i*arg(z)}.
It returns log(x+i*y) = log(|z|)+i*arg(z).
The evaluation of |z| calls the square root routine,
then a formula
    log(|z|) = (1/2)*log(x*x+y*y)
is used.
**************************************************/
#ifndef SN_H
#include "sn.h"
#endif
SComplex Clog(const SComplex& z){
    SDouble r = z.Norm();   // r = x*x+y*y
    if(r.Sign() == 0) r.SetError(r.DOMAIN_ERR, "Clog z=0", 9108);// z = 0
    r = Log(r)/2.0;         // r = log |z|
    return SComplex(r, Arg(z));
}