Improved documentation.

src/main/java/org/orekit/propagation/BaseJacobianColumnGenerator.java

@@ -25,6 +25,21 @@ import org.orekit.orbits.OrbitType;
 import org.orekit.orbits.PositionAngle;
 
 /** Base generator for one column of a Jacobian matrix.
+ * <p>
+ * Specialized versions of this class are used when estimating
+ * parameters (for example propagation parameters like drag coefficient,
+ * thrust or maneuver start date) in orbit determination or maneuver
+ * optimization.
+ * </p>
+ * <p>
+ * Some implementations may be based on closed-form expressions and
+ * will implement the {@link AdditionalStateProvider} interface whereas
+ * otherimplementations may be based on differential equations and will
+ * implement the {@link
+ * org.orekit.propagation.integration.AdditionalDerivativesProvider
+ * AdditionalDerivativesProvider} interface). This base class therefore
+ * does not specify how the column is generated and put into the state.
+ * </p>
  * @author Luc Maisonobe
  * @since 11.1
  */

src/main/java/org/orekit/propagation/TriggerDateJacobianColumnGenerator.java

@@ -52,7 +52,7 @@ import org.orekit.forces.maneuvers.trigger.ManeuverTriggersResetter;
  * \[\frac{\partial y_t}{\partial y_1} = \frac{\partial y_t}{\partial y_0} \left(\frac{\partial y_1}{\partial y_0}\right)^{-1}\].
  * </p>
  * <p>
- * The Jacobian column can therefore be computed using the closed-form expression:
+ * The Jacobian column can therefore be computed using the following closed-form expression:
  * \[\frac{\partial y_t}{\partial t_1}
  * = \pm \frac{\partial y_t}{\partial y_0} \left(\frac{\partial y_1}{\partial y_0}\right)^{-1} f_m(t_1, y_1)
  * = \frac{\partial y_t}{\partial y_0} c_1\]
@@ -60,6 +60,11 @@ import org.orekit.forces.maneuvers.trigger.ManeuverTriggersResetter;
  * by solving \(\frac{\partial y_1}{\partial y_0} c_1 = \pm f_m(t_1, y_1)\).
  * </p>
  * <p>
+ * As the column is generated using a closed-form expression, this generator implements
+ * the {@link AdditionalStateProvider} interface and stores the column directly
+ * in the premiary state during propagation.
+ * </p>
+ * <p>
  * The implementation takes care to <em>not</em> resetting anything at propagation start.
  * This allows to get proper Jacobian if we interrupt propagation in the middle of a maneuver
  * and restart propagation where it left.

src/main/java/org/orekit/propagation/numerical/IntegrableJacobianColumnGenerator.java

@@ -21,6 +21,12 @@ import org.orekit.propagation.SpacecraftState;
 import org.orekit.propagation.integration.AdditionalDerivativesProvider;
 
 /** Generator for one column of a Jacobian matrix.
+ * <p>
+ * This generator is based on variational equations, so
+ * it implements {@link AdditionalDerivativesProvider} and
+ * computes only the derivative of the Jacobian column, to
+ * be integrated by the propagator alongside the primary state.
+ * </p>
  * @author Luc Maisonobe
  * @since 11.1
  */