RELEASE-NOTES.txt

              Hipparchus 1.5 RELEASE NOTES

The Hipparchus team is pleased to announce the release of hipparchus-1.5

The Hipparchus library is a library of mathematical components. It started as a fork of Apache Commons Math.

This is a maintenance release. The main changes since last version are the introduction of field versions
of bilinear interpolation, univariate interpolators, polynomials and polynomial spline functions,
and the introduction of reset events in ODE.

Changes in this version include:

New features:
o issues/55:  Added FieldBivariateFunction and make both BilinearInterpolatingFunction
              and PiecewiseBicubicSplineInterpolatingFunction implement it.
              Github: fixes #55. 
o             Added FieldUnivariateInterpolator and make both LinearInterpolator,
              AkimaSplineInterpolator and SplineInterpolator implement it. 
o             Added FieldPolynomialFunction and FieldPolynomialSplineFunction. 
o             Add Action.RESET_EVENTS to ask the integrator to recheck all event detectors
              without recomputing the step. Use when the g function of one event detector
              depends on events occurring in another event detector. 
o issues/53:  Fixed documentation for interpolation algorithms.
              Github: fixes #53. 

Fixed Bugs:
o             Nullify corrected state after predict in abstract Kalman filter. Note that this affects
              only custom extensions of AbstractKalmanFilter because the implementations provided
              by Hipparchus (LinearKalmanFilter and ExtendedKalmanFilter) always call correction
              step after having called prediction step, so the nullified corrected state is reset
              properly at the end. This was initially reported as
              https://gitlab.orekit.org/orekit/orekit/issues/540. Thanks to Hao Peng. 
o issues/54:  Avoid too many multi-step integrator restarts after event resetting derivatives.
              Github: fixes #54. 

Changes:
o           MatrixUtils.createDiagonalMatrix now creates instances of DiagonalMatrix,
            not general RealMatrix. 


For complete information on Hipparchus, including instructions on how to submit bug reports,
patches, or suggestions for improvement, see the Hipparchus website:

https://www.hipparchus.org/