protected static Ptg calcSign( Ptg[] operands )
	{
		if( operands.length != 1 )
		{
			return PtgCalculator.getNAError();
		}
		double dd = 0.0;
		try
		{
			dd = operands[0].getDoubleVal();
		}
		catch( NumberFormatException e )
		{
			return PtgCalculator.getValueError();
		}
		int res = 0;
		if( new Double( dd ).isNaN() )
		{
			return PtgCalculator.getError(); // Not a Num -- possibly PtgErr
		}
		if( dd == 0 )
		{
			res = 0;
		}
		if( dd > 0 )
		{
			res = 1;
		}
		if( dd < 0 )
		{
			res = -1;
		}
		PtgInt pint = new PtgInt( res );
		return pint;
	}