Super duper mega (fun!) commit: replaced encoding=utf-8 with fileencoding=utf-8 in...

[inkscape.git] / src / 2geom / numeric / fitting-model.h

diff --git a/src/2geom/numeric/fitting-model.h b/src/2geom/numeric/fitting-model.h
index cc31133727079f7fb2eb2c140d9f7a73df88d169..dcf0e8e1d71d79e4f76ca042a6c2df6fe94804d2 100644 (file)
--- a/src/2geom/numeric/fitting-model.h
+++ b/src/2geom/numeric/fitting-model.h
@@ -41,11 +41,36 @@
 #include <2geom/bezier-curve.h>
 #include <2geom/poly.h>
 #include <2geom/ellipse.h>
+#include <2geom/circle.h>
 #include <2geom/utils.h>
 
 
 namespace Geom { namespace NL {
 
+/*
+ * A model is an abstraction for an expression dependent from a parameter where
+ * the coefficients of this expression are the unknowns of the fitting problem.
+ * For a ceratain number of parameter values we know the related values
+ * the expression evaluates to: from each parameter value we get a row of
+ * the matrix of the fitting problem, from each expression value we get
+ * the related constant term.
+ * Example: given the model a*x^2 + b*x + c = 0; from x = 1 we get
+ * the equation a + b + c = 0, in this example the constant term is always
+ * the same for each parameter value.
+ *
+ * A model is required to implement 3 methods:
+ *
+ *  - size : returns the number of unknown coefficients that appear in
+ *           the expression of the fitting problem;
+ *  - feed : its input is a parameter value and the related expression value,
+ *           it generates a matrix row and a new entry of the constant vector
+ *           of the fitting problem;
+ *  - instance : it has an input parameter represented by the raw vector
+ *               solution of the fitting problem and an output parameter
+ *               of type InstanceType that return a specific object that is
+ *               generated using the fitting problem solution, in the example
+ *               above the object could be a Poly type.
+ */
 
 /*
  *   completely unknown models must inherit from this template class;
@@ -239,6 +264,41 @@ class LFMEllipse
 };
 
 
+// incomplete model, it can be inherited to make up different kinds of
+// instance type; the raw data is a vector of coefficients of the equation
+// of a circle curve
+template< typename InstanceType >
+class LFMCircleEquation
+    : public LinearFittingModelWithFixedTerms<Point, double, InstanceType>
+{
+  public:
+    void feed( VectorView & coeff, double & fixed_term, Point const& p ) const
+    {
+        coeff[0] = p[X];
+        coeff[1] = p[Y];
+        coeff[2] = 1;
+        fixed_term = p[X] * p[X] + p[Y] * p[Y];
+    }
+
+    size_t size() const
+    {
+        return 3;
+    }
+};
+
+
+// this model generates Ellipse curves
+class LFMCircle
+    : public LFMCircleEquation<Circle>
+{
+  public:
+    void instance(Circle & c, ConstVectorView const& coeff) const
+    {
+        c.set(1, coeff[0], coeff[1], coeff[2]);
+    }
+};
+
+
 // this model generates SBasis objects
 class LFMSBasis
     : public LinearFittingModel<double, double, SBasis>
@@ -420,4 +480,4 @@ class LFMBezierCurve
   fill-column:99
   End:
 */
-// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:encoding=utf-8:textwidth=99 :
+// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:fileencoding=utf-8:textwidth=99 :