public Sequence eval(StaticContext context, DocumentSet docs, Sequence contextSequence, Item contextItem)
public Sequence eval(DocumentSet docs, Sequence contextSequence, Item contextItem)
	public Sequence eval(StaticContext context, DocumentSet docs, Sequence contextSequence, Item contextItem) 	throws XPathException {		if(contextItem != null)			contextSequence = contextItem.toSequence();		double lvalue = 			((DoubleValue)getLeft().eval(context, docs, contextSequence).convertTo(Type.DECIMAL)).getDouble();		double rvalue = 			((DoubleValue)getRight().eval(context, docs, contextSequence).convertTo(Type.DECIMAL)).getDouble();		double result = applyOperator(lvalue, rvalue);		return new DoubleValue(result);	}