Address comments (idaholab#14220)

framework/doc/content/source/functions/CoarsenedPiecewiseLinear.md

@@ -1,4 +1,4 @@
-# PiecewiseLinear
+# CoarsenedPiecewiseLinear
 
 !syntax description /Functions/CoarsenedPiecewiseLinear
 

framework/doc/content/source/vectorpostprocessors/PiecewiseFunctionTabulate.md

@@ -2,8 +2,12 @@
 
 !syntax description /VectorPostprocessors/PiecewiseFunctionTabulate
 
-This object can be used to check the function generated by a
-[`CoarsenedPiecewiseLinear`](/CoarsenedPiecewiseLinear.md) function.
+This object can be used to check the function generated by a 2D piecewise
+defined function, such as
+
+- [`PiecewiseConstant`](/PiecewiseConstant.md)
+- [`PiecewiseLinear`](/PiecewiseLinear.md)
+- [`CoarsenedPiecewiseLinear`](/CoarsenedPiecewiseLinear.md).
 
 !syntax parameters /VectorPostprocessors/PiecewiseFunctionTabulate
 

framework/include/functions/CoarsenedPiecewiseLinear.h

@@ -17,7 +17,10 @@ template <>
 InputParameters validParams<CoarsenedPiecewiseLinear>();
 
 /**
- * Perform a point reduction of the tabulated data upon initialization.
+ * Function class that reads in a list of (x,y) value pairs representing a pointwise defined
+ * function sililar to PiecewiseLinear. In addition this Function object performs a point reduction
+ * of the tabulated data upon initialization resulting in the evaluation of a simplified function
+ * with fewer data points.
  */
 class CoarsenedPiecewiseLinear : public PiecewiseLinearBase
 {

framework/include/functions/PiecewiseBase.h

@@ -19,9 +19,9 @@ InputParameters validParams<PiecewiseBase>();
 
 /**
  * Function base which provides a piecewise approximation to a provided
- * (x,y) point data set.  Derived classes which control the order
+ * (x,y) point data set.  Derived classes, which control the order
  * (constant, linear) of the approximation and how the (x,y) data set
- * is generated. should be used directly,
+ * is generated, should be used directly.
  */
 class PiecewiseBase : public Function
 {

framework/include/functions/PiecewiseLinearBase.h

@@ -18,34 +18,18 @@ template <>
 InputParameters validParams<PiecewiseLinearBase>();
 
 /**
- * Function which provides a piecewise continuous linear interpolation
- * of a provided (x,y) point data set.
+ * Base class for functions which provides a piecewise continuous linear
+ * interpolation of an (x,y) point data set.
  */
 class PiecewiseLinearBase : public PiecewiseBase
 {
 public:
   PiecewiseLinearBase(const InputParameters & parameters);
 
   virtual void initialSetup() override;
-
-  /**
-   * Get the value of the function (based on time only)
-   * \param t The time
-   * \param pt The point in space (x,y,z) (unused)
-   * \return The value of the function at the specified time
-   */
   virtual Real value(Real t, const Point & pt) const override;
-
-  /**
-   * Get the time derivative of the function (based on time only)
-   * \param t The time
-   * \param pt The point in space (x,y,z) (unused)
-   * \return The time derivative of the function at the specified time
-   */
   virtual Real timeDerivative(Real t, const Point & pt) const override;
-
   virtual Real integral() const override;
-
   virtual Real average() const override;
 
 protected:

framework/include/utils/PointReduction.h

@@ -18,12 +18,24 @@ namespace PointReduction
 typedef std::pair<Real, Real> FunctionNode;
 typedef std::vector<FunctionNode> FunctionNodeList;
 
-/// compute the perpendicular distance of a point from a line defined by begin and end points
+/**
+ * compute the perpendicular distance of a point P from a line defined by begin
+ * and end points.
+ *
+ * @param point The (x,y) point P
+ * @param begin The first (x,y) point defining the line to compute the distance to
+ * @param end The second (x,y) point defining the line to compute the distance to
+ */
 Real perpendicularDistance(const FunctionNode & point,
                            const FunctionNode & begin,
                            const FunctionNode & end);
 
-/// return a pruned function node list using the Ramer-Douglas-Peucker algorithm
+/**
+ * Generate a pruned function node list using the Ramer-Douglas-Peucker algorithm.
+ *
+ * @param list An ordered (by x) list of (x,y) points defining a pointwise defined function.
+ * @param epsilon The Ramer-Douglas-Peucker tolerance parameter for coarsening.
+ */
 FunctionNodeList douglasPeucker(const FunctionNodeList &, Real epsilon);
 
 } // namespace PointReduction

framework/include/vectorpostprocessors/PiecewiseFunctionTabulate.h

@@ -31,7 +31,12 @@ class PiecewiseFunctionTabulate : public GeneralVectorPostprocessor
   virtual void finalize() override {}
 
 protected:
+  /// The piecewise function to tabulate
   const PiecewiseBase * _piecewise_function;
+
+  /// function argument (x) column
   VectorPostprocessorValue & _x_col;
+
+  /// function value (x) column
   VectorPostprocessorValue & _y_col;
 };

framework/src/utils/PointReduction.C

@@ -8,6 +8,7 @@
 //* https://www.gnu.org/licenses/lgpl-2.1.html
 
 #include "PointReduction.h"
+#include "MooseUtils.h"
 #include "MooseError.h"
 
 #include <algorithm>
@@ -35,7 +36,8 @@ perpendicularDistance(const FunctionNode & node,
   const Real y2 = end.second;
 
   const Real denom = std::sqrt(sqr(y2 - y1) + sqr(x2 - x1));
-  mooseAssert(denom > 0, "Line begin and end points bust not be the same");
+  mooseAssert(MooseUtils::absoluteFuzzyGreaterThan(denom, 0.0),
+              "Line begin and end points must not be the same");
 
   return std::abs((y2 - y1) * x0 - (x2 - x1) * y0 + x2 * y1 - y2 * x1) / denom;
 }
@@ -47,7 +49,7 @@ douglasPeuckerRecurse(const FunctionNodeList & list,
                       std::size_t begin,
                       std::size_t end)
 {
-  // Find the point with the maximum distance
+  // Find the point with the maximum distance from the line defined by begin and end
   Real dmax = 0.0;
   std::size_t index = 0;
 

test/tests/functions/coarsened_piecewise_linear/tests

@@ -12,7 +12,7 @@
     type = 'CSVDiff'
     input = 'coarsened_piecewise_linear.i'
     csvdiff = 'coarsened_piecewise_linear_vpp_F_0000.csv'
-    requirement = "The Function system shall include an object that creates a function based on x- and y-data pairs and returns an explicit value from the supplied data when queried (i.e., linear interpolation is not performed)."
+    requirement = "The Function system shall include an object that creates a function based on x- and y-data pairs, reduces the number of data points based on a user supplied cut-off and returns a linearly interpolated value from the coarsened data."
     prereq = 'prepare_data'
   [../]
 []