Updates to docs // renamed Coordinate::getQDot to Coordinate::getQDot…

…Value

OpenSim/Simulation/Model/FunctionBasedPath.cpp

@@ -26,7 +26,7 @@
 
 using namespace OpenSim;
 
-const std::string FunctionBasedPath::LENGTH_NAME("length_cache");
+const std::string FunctionBasedPath::LENGTH_NAME("length");
 const std::string FunctionBasedPath::LENGTHENING_SPEED_NAME("lengthening_speed");
 const std::string FunctionBasedPath::MOMENT_ARMS_NAME("moment_arms");
 
@@ -179,7 +179,7 @@ SimTK::Vector FunctionBasedPath::computeCoordinateSpeeds(
 {
     SimTK::Vector coordinateSpeeds((int)_coordinates.size(), 0.0);
     for (int i = 0; i < (int)_coordinates.size(); ++i) {
-        coordinateSpeeds[i] = _coordinates[i]->getQDot(s);
+        coordinateSpeeds[i] = _coordinates[i]->getQDotValue(s);
     }
 
     return coordinateSpeeds;

OpenSim/Simulation/Model/FunctionBasedPath.h

@@ -44,26 +44,27 @@ namespace OpenSim {
  * path length, lengthening speed, and moment arms are a priority (e.g., a 
  * direct collocation problem).
  * 
- * Each instance of this class requires a list of model coordinates that the
- * path is dependent on and a function, \f$ l(q) \f$, that computes the length 
- * of the path as a function of the coordinate values, \f$ q \f$. Optionally, 
- * the user can provide functions that compute the moment arms of the path as a 
- * function of the coordinate values and a function that computes the speed of 
- * the path as a function of the coordinate values and speeds. 
+ * Each instance of this class requires both a list of model coordinates that 
+ * the path is dependent on and a function, \f$ l(q) \f$, that computes the 
+ * length of the path as a function of the coordinate values, \f$ q \f$. 
+ * Optionally, functions can be provided to compute the moment arms of the path 
+ * as a function of the coordinate values and a function that computes the speed 
+ * of the path as a function of the coordinate values and speeds. 
  * 
  * If the moment arm functions are not provided, the moment arms will be 
  * computed from the derivative of the length function with respect to the 
  * coordinate values: 
  * 
  * \f[
- * r_i = \frac{\partial l}{\partial q_i}
+ * r_i = \frac{\partial l}{\partial q_i} \quad i = 1, \ldots, N_q
  * \f]
  * 
  *  * Where, 
  * - \f$ l \f$: the length of the path.
  * - \f$ q \f$: the set of coordinate values.
  * - \f$ r_i \f$: the moment arm of the path with respect to the \f$ i^{th} \f$
  * coordinate.
+ * - \f$ N_q \f$: the number of coordinates.
  * 
  * If the speed function is not provided, the speed will be computed using the 
  * dot product of the moment arms and coordinate speeds based on the chain rule:
@@ -77,7 +78,6 @@ namespace OpenSim {
  * Where, 
  * - \f$ dot{l} \f$: the lengthening speed of the path.
  * - \f$ dot{q} \f$: the set of coordinate speeds.
- * - \f$ N_q \f$: the number of coordinates.
  * 
  * The length function and the moment arm functions (if provided) must have the 
  * same number of arguments as the number of coordinates, where the order of the 

OpenSim/Simulation/SimbodyEngine/Coordinate.cpp

@@ -370,7 +370,7 @@ const std::string&  Coordinate::getSpeedName() const
     return _speedName;
 }
 
-double Coordinate::getQDot(const SimTK::State& s) const {
+double Coordinate::getQDotValue(const SimTK::State& s) const {
     return _model->getMatterSubsystem().getMobilizedBody(_bodyIndex).getOneQDot(s,_mobilizerQIndex);
 }
 

OpenSim/Simulation/SimbodyEngine/Coordinate.h

@@ -154,7 +154,9 @@ OpenSim_DECLARE_CONCRETE_OBJECT(Coordinate, ModelComponent);
         state variable. Returns the string "<coordinate_name>/speed" */
     const std::string& getSpeedName() const;
 
-    double getQDot(const SimTK::State& s) const;
+    /** get the derivative of Coordinate's value from the state. This value is
+        *not* necessarily equal to the value returned by getSpeedValue(). */
+    double getQDotValue(const SimTK::State& s) const;
 
     /** get the default value for this coordinate. This is the value 
         used if no value has been set prior to a simulation. */