if (BigInteger.negate(words, x.words, len))
if (negate(words, x.words, len))
  private void setNegative(BigInteger x)  {    int len = x.ival;    if (x.words == null)      {	if (len == Integer.MIN_VALUE)	  set(- (long) len);	else	  set(-len);	return;      }    realloc(len + 1);    if (BigInteger.negate(words, x.words, len))      words[len++] = 0;    ival = len;  }