UKFAndEKFNLSpring:

 Simulate a UKF and EKF with a nonlinear spring example.

   Things to try:
   1. Change the noise numbers.
   2. Make the spring constant different for the spring and estimator.

   Since version 11.
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Children:

Common: DemoFuns/GXUKF
Common: DemoFuns/RHSUKF
Common: Estimation/EKFPredict
Common: Estimation/EKFUpdate
Common: Estimation/FXNLSpring
Common: Estimation/KFInitialize
Common: Estimation/UKFPredict
Common: Estimation/UKFUpdate
Common: Estimation/UKFWeight
Common: Graphics/Plot2D
Math: Integration/RK4