/*  scfsinbs.cpp  by K.Tsuru  */
// function ID = 9122 since ver.2.18
/*****************************************
SComplex class
It returns cos(z) using binary splitting method.
Let z = x+iy,
sin(z) = sin(x)*cosh(y)+i*cos(x)sinh(y).
*****************************************/
#ifndef SN_H
#include "sn.h"
#endif
SComplex CsinBS(const SComplex& z){
    SDouble c, s, ch, sh;
    CosSinBS(z.Real(), c, s);   // c = cos(x), s = sin(x)
    SDouble e, r;
    int is = z.Imag().Sign(9122);

    if(is > 0) {    // y > 0
        e = ExpBS(z.Imag());    // = exp(y)
        r = 1/e;
        ch = DDiv2(e + r);      // = cosh(y)
        sh = ch - r;            // = sinh(y)
    } else if(is == 0) {    // y = 0
        ch = 1;     sh = 0.0;
    } else {    // y < 0
        e = ExpBS(-z.Imag());   // = exp(-y)
        r = 1/e;
        ch = DDiv2(e + r);      // = cosh(-y)
        sh = ch - e;            // = -sinh(-y)
    }
    return SComplex(s * ch, c * sh);
}