public DoubleConstant addDouble(double value){
  DoubleConstant entry=getDoubleByValue(value);
  if (entry != null)   return entry;
  entry=new DoubleConstant(this,_entries.size(),value);
  addConstant(entry);
  addConstant(null);
  return entry;
}

public DoubleConstant addDouble ( double value ) { DoubleConstant entry = getDoubleByValue ( value ) ; if ( entry != null ) return entry ; entry = new DoubleConstant ( this , _entries . size ( ) , value ) ; addConstant ( entry ) ; addConstant ( null ) ; return entry ; }
adds a double constant .
