//! initializes from passed-in xml element, in format <someelement x="..." y="..." z="..." s="..."/>
public Rot( XmlElement xmlelement )
{
x = Convert.ToDouble( xmlelement.GetAttribute( "x" ) );
y = Convert.ToDouble( xmlelement.GetAttribute( "y" ) );
z = Convert.ToDouble( xmlelement.GetAttribute( "z" ) );
s = Convert.ToDouble( xmlelement.GetAttribute( "s" ) );
}