/*  sxfbcos.cpp  by K.Tsuru  */
// function ID 5201     BRADIX
#ifndef SN_H
#include "sn.h"
#endif
/**************
SDecimal class
cos x
****************/
SDecimal Bcos(const SDouble& x){
    SDecimal r;
    SDouble y;

    int func = COS_CALC;
    int s = GetTriCalcMethod(x, y, &func);
    if(s == 0){
        r = y.Sign(5201);   // y = -1, 0, 1
        // must return SDecimal object.
        x.upToTerm = 1;
    } else if(func == COS_CALC) r = BcosSeries(y);
    else r = BsinSeries(y);

    if(s < 0) r.ChangeSign();   // r = -r;
    return r;
}