public void GetKnownDisplacementVector()
{
KeyedVector <NodalDegreeOfFreedom> result = SUT.KnownDisplacementVector();
Assert.IsNotNull(result);
Assert.AreEqual(2, result.Count);
// can be accessed by a key
NodalDegreeOfFreedom ndof1 = new NodalDegreeOfFreedom(node1, DegreeOfFreedom.X);
NodalDegreeOfFreedom ndof2 = new NodalDegreeOfFreedom(node3, DegreeOfFreedom.X);
Assert.AreEqual(0, result[ndof1]);
Assert.AreEqual(0, result[ndof2]);
}