/*  sdominus.cpp  by K.Tsuru  */
// function ID = 331  DRADIX
/***************************************
SDouble class
It provides the subtraction operator-().
It returns "m-n".
****************************************/
#ifndef SN_H
#include "sn.h"
#endif
SDouble operator-(const SDouble& m, const SDouble& n){
    if((m.Type() != m.REAL)||(n.Type() != n.REAL)) m.SetError(m.RADIX_ERR, "SD -", 331);
    int sgn = m.Sign(331)*n.Sign(331), c;
    if( sgn == 0 ){             //m and/or n =0
        if( m.Sign() == 0 ) return -n;
        else                return  m;
    } else if(sgn < 0){         //different sign m - n = m + (-n)
        return DDAdd(m, -n);    //The sign is the same that of m, set in DDAdd().
    } else {                    //same sign
        c = DDCompare(m, n);
        if(c > 0)   return DDSub(m, n);     //|m|>|n|, The sign is same as that of m,set in DDSub().
        else if(c)  return -DDSub(n, m);    //|m|<|n|, m-n=-(n-m)
        else return 0.0;    // c = 0 : m = n  result = 0
    }
}