Refined interface for Conjugate Gradient

Some interface was refined (most notably, the method for returning
Hessian was removed and the method for getting gradient was added as
optional to base Solver::Function class) and basic code for
setters/getters was added. Now is the time for the real work on an
algorithm.

modules/optim/doc/conjugate_gradient.rst

+Conjugate Gradient
+=======================
+
+.. highlight:: cpp
+
+optim::ConjGradSolver
+---------------------------------
+
+.. ocv:class:: optim::ConjGradSolver
+
+This class is used

modules/optim/include/opencv2/optim.hpp

@@ -55,6 +55,7 @@ public:
     public:
        virtual ~Function() {}
        virtual double calc(const double* x) const = 0;
+       virtual void getGradient(const double* /*x*/,double* /*grad*/) {}
     };
 
     virtual Ptr<Function> getFunction() const = 0;
@@ -86,17 +87,7 @@ CV_EXPORTS_W Ptr<DownhillSolver> createDownhillSolver(const Ptr<Solver::Function
         TermCriteria termcrit=TermCriteria(TermCriteria::MAX_ITER+TermCriteria::EPS,5000,0.000001));
 
 //! conjugate gradient method
-class CV_EXPORTS ConjGradSolver : public Solver
-{
-public:
-    class CV_EXPORTS Function : public Solver::Function
-    {
-    public:
-       //! gradient is like the first derivative for multivar function
-       virtual void getGradient(const double* x,double* buf)const=0;
-       //! Jacobian is like the second derivative
-       virtual void getJacobian(const double* x)const=0;
-    };
+class CV_EXPORTS ConjGradSolver : public Solver{
 };
 
 CV_EXPORTS_W Ptr<ConjGradSolver> createConjGradSolver(const Ptr<Solver::Function>& f=Ptr<ConjGradSolver::Function>(),

modules/optim/src/conjugate_gradient.cpp

+#include "precomp.hpp"
+#include "debug.hpp"
+
+namespace cv{namespace optim{
+
+    class ConjGradSolverImpl : public ConjGradSolver
+    {
+    public:
+        Ptr<Function> getFunction() const;
+        void setFunction(const Ptr<Function>& f);
+        TermCriteria getTermCriteria() const;
+        ConjGradSolverImpl();
+        void setTermCriteria(const TermCriteria& termcrit);
+        double minimize(InputOutputArray x);
+    protected:
+        Ptr<Solver::Function> _Function;
+        TermCriteria _termcrit;
+        Mat_<double> d,r,buf_x,r_old;
+    private:
+    };
+
+    double ConjGradSolverImpl::minimize(InputOutputArray x){
+        CV_Assert(_Function.empty()==false);
+        dprintf(("termcrit:\n\ttype: %d\n\tmaxCount: %d\n\tEPS: %g\n",_termcrit.type,_termcrit.maxCount,_termcrit.epsilon));
+
+        Mat x_mat=x.getMat();
+        CV_Assert(MIN(x_mat.rows,x_mat.cols)==1);
+        int ndim=MAX(x_mat.rows,x_mat.cols);
+        CV_Assert(x_mat.type()==CV_64FC1);
+
+        d.create(1,ndim);
+        r.create(1,ndim);
+        r_old.create(1,ndim);
+
+        Mat_<double> proxy_x;
+        if(x_mat.rows>1){
+            buf_x.create(1,ndim);
+            Mat_<double> proxy(ndim,1,(double*)buf_x.data);
+            x_mat.copyTo(proxy);
+            proxy_x=buf_x;
+        }else{
+            proxy_x=x_mat;
+        }
+
+        //here everything goes. check that everything is setted properly
+
+        if(x_mat.rows>1){
+            Mat(ndim, 1, CV_64F, (double*)proxy_x.data).copyTo(x);
+        }
+        return 0.0;
+    }
+    ConjGradSolverImpl::ConjGradSolverImpl(){
+        _Function=Ptr<Function>();
+    }
+    Ptr<Solver::Function> ConjGradSolverImpl::getFunction()const{
+        return _Function;
+    }
+    void ConjGradSolverImpl::setFunction(const Ptr<Function>& f){
+        _Function=f;
+    }
+    TermCriteria ConjGradSolverImpl::getTermCriteria()const{
+        return _termcrit;
+    }
+    void ConjGradSolverImpl::setTermCriteria(const TermCriteria& termcrit){
+        CV_Assert((termcrit.type==(TermCriteria::MAX_ITER+TermCriteria::EPS) && termcrit.epsilon>0 && termcrit.maxCount>0) ||
+                ((termcrit.type==TermCriteria::MAX_ITER) && termcrit.maxCount>0));
+        _termcrit=termcrit;
+    }
+    // both minRange & minError are specified by termcrit.epsilon; In addition, user may specify the number of iterations that the algorithm does.
+    Ptr<ConjGradSolver> createConjGradSolver(const Ptr<Solver::Function>& f, TermCriteria termcrit){
+        ConjGradSolver *CG=new ConjGradSolverImpl();
+        CG->setFunction(f);
+        CG->setTermCriteria(termcrit);
+        return Ptr<ConjGradSolver>(CG);
+    }
+}}
+                               

modules/optim/src/simplex.cpp

@@ -19,6 +19,8 @@ namespace cv{namespace optim{
         Ptr<Solver::Function> _Function;
         TermCriteria _termcrit;
         Mat _step;
+        Mat_<double> buf_x;
+
     private:
         inline void createInitialSimplex(Mat_<double>& simplex,Mat& step);
         inline double innerDownhillSimplex(cv::Mat_<double>& p,double MinRange,double MinError,int& nfunk,
@@ -209,7 +211,10 @@ namespace cv{namespace optim{
         Mat_<double> proxy_x;
 
         if(x_mat.rows>1){
-            proxy_x=x_mat.t();
+            buf_x.create(1,_step.cols);
+            Mat_<double> proxy(_step.cols,1,(double*)buf_x.data);
+            x_mat.copyTo(proxy);
+            proxy_x=buf_x;
         }else{
             proxy_x=x_mat;
         }

modules/optim/test/test_conjugate_gradient.cpp

+#include "test_precomp.hpp"
+#include <cstdlib>
+
+static void mytest(cv::Ptr<cv::optim::ConjGradSolver> solver,cv::Ptr<cv::optim::Solver::Function> ptr_F,cv::Mat& x,
+        cv::Mat& etalon_x,double etalon_res){
+    solver->setFunction(ptr_F);
+    //int ndim=MAX(step.cols,step.rows);
+    double res=solver->minimize(x);
+    std::cout<<"res:\n\t"<<res<<std::endl;
+    std::cout<<"x:\n\t"<<x<<std::endl;
+    std::cout<<"etalon_res:\n\t"<<etalon_res<<std::endl;
+    std::cout<<"etalon_x:\n\t"<<etalon_x<<std::endl;
+    double tol=solver->getTermCriteria().epsilon;
+    ASSERT_TRUE(std::abs(res-etalon_res)<tol);
+    /*for(cv::Mat_<double>::iterator it1=x.begin<double>(),it2=etalon_x.begin<double>();it1!=x.end<double>();it1++,it2++){
+        ASSERT_TRUE(std::abs((*it1)-(*it2))<tol);
+    }*/
+    std::cout<<"--------------------------\n";
+}
+
+class SphereF:public cv::optim::Solver::Function{
+public:
+    double calc(const double* x)const{
+        return x[0]*x[0]+x[1]*x[1]+x[2]*x[2]+x[3]*x[3];
+    }
+    void getGradient(const double* x,double* grad){
+        for(int i=0;i<4;i++,grad++,x++){
+            grad[0]=2*x[0];
+        }
+    }
+};
+//TODO: test transp/usual x
+/*class RosenbrockF:public cv::optim::Solver::Function{
+    double calc(const double* x)const{
+        return 100*(x[1]-x[0]*x[0])*(x[1]-x[0]*x[0])+(1-x[0])*(1-x[0]);
+    }
+};*/
+
+TEST(Optim_ConjGrad, regression_basic){
+    cv::Ptr<cv::optim::ConjGradSolver> solver=cv::optim::createConjGradSolver();
+#if 1
+    {
+        cv::Ptr<cv::optim::Solver::Function> ptr_F(new SphereF());
+        cv::Mat x=(cv::Mat_<double>(1,2)<<1.0,1.0),
+            etalon_x=(cv::Mat_<double>(1,2)<<0.0,0.0);
+        double etalon_res=0.0;
+        return;
+        mytest(solver,ptr_F,x,etalon_x,etalon_res);
+    }
+#endif
+#if 0
+    {
+        cv::Ptr<cv::optim::Solver::Function> ptr_F(new RosenbrockF());
+        cv::Mat x=(cv::Mat_<double>(2,1)<<0.0,0.0),
+            step=(cv::Mat_<double>(2,1)<<0.5,+0.5),
+            etalon_x=(cv::Mat_<double>(2,1)<<1.0,1.0);
+        double etalon_res=0.0;
+        mytest(solver,ptr_F,x,step,etalon_x,etalon_res);
+    }
+#endif
+}