/*  sffberni.cpp  by K.Tsuru  */
// function ID 7100     DRADIX
/*****************************************************************
SFraction class
It provides the n-th Bernoulli's number Bn by use of TanCoeff(n).
******************************************************************/
#ifndef SN_H
#include "sn.h"
#endif

SFraction BernNum(uint n){
    SLong den;
    if(n >= den.Radix()/2u) den.SetError(den.OUT_OF_RANGE,"BernNum", 7100);
    if(!n){ TanCoeff(0);    return 0.0; } // free memory.

    SLong Tn2n = (2*n)*TanCoeff(n);

    den = Lpow(4, n);       // den = 2^(2n)
    den = den*(den -1L);

    SFraction r(Tn2n, den);
    r.Reduce();
    return r;
}