public void GetKnownForceVector()
{
KeyedVector <NodalDegreeOfFreedom> result = SUT.KnownForceVector();
Assert.IsNotNull(result);
Assert.AreEqual(1, result.Count);
// can be accessed by a key
NodalDegreeOfFreedom ndof1 = new NodalDegreeOfFreedom(node2, DegreeOfFreedom.X);
Assert.AreEqual(20, result[ndof1]);
}