Merge pull request #80 from Huangzizhou/slim

smooth_step after line search for slim

Author: Huangzizhou

src/polysolve/nonlinear/Problem.hpp

@@ -90,6 +90,8 @@ namespace polysolve::nonlinear
         /// @param new_x New solution.
         virtual void solution_changed(const TVector &new_x) {}
 
+        virtual bool after_line_search_custom_operation(const TVector &x0, const TVector &x1) { return false; }
+
         /// @brief Callback function used to determine if the solver should stop.
         /// @param state Current state of the solver.
         /// @param x Current solution.

src/polysolve/nonlinear/Solver.cpp

@@ -427,7 +427,13 @@ namespace polysolve::nonlinear
                 continue;
             }
 
-            x += rate * delta_x;
+            {
+                TVector x1 = x + rate * delta_x;
+                if (objFunc.after_line_search_custom_operation(x, x1))
+                    objFunc.solution_changed(x1);
+                x = x1;
+            }
+
             old_energy = energy;
 
             // Reset this for the next iterations
@@ -574,6 +580,7 @@ namespace polysolve::nonlinear
     void Solver::verify_gradient(Problem &objFunc, const TVector &x, const TVector &grad)
     {
         bool match = false;
+        double J = objFunc(x);
 
         switch (gradient_fd_strategy)
         {
@@ -591,16 +598,18 @@ namespace polysolve::nonlinear
             objFunc.solution_changed(x1);
             double J1 = objFunc(x1);
 
-            double fd = (J2 - J1) / 2 / gradient_fd_eps;
+            double fd_centered = (J2 - J1) / 2 / gradient_fd_eps;
+            double fd_right = (J2 - J) / gradient_fd_eps;
+            double fd_left = (J - J1) / gradient_fd_eps;
             double analytic = direc.dot(grad);
 
-            match = abs(fd - analytic) < 1e-8 || abs(fd - analytic) < 1e-4 * abs(analytic);
+            match = abs(fd_centered - analytic) < 1e-8 || abs(fd_centered - analytic) < 1e-4 * abs(analytic);
 
             // Log error in either case to make it more visible in the logs.
             if (match)
-                m_logger.debug("step size: {}, finite difference: {}, derivative: {}", gradient_fd_eps, fd, analytic);
+                m_logger.debug("step size: {}, finite difference: {} {} {}, derivative: {}", gradient_fd_eps, fd_centered, fd_left, fd_right, analytic);
             else
-                m_logger.error("step size: {}, finite difference: {}, derivative: {}", gradient_fd_eps, fd, analytic);
+                m_logger.error("step size: {}, finite difference: {} {} {}, derivative: {}", gradient_fd_eps, fd_centered, fd_left, fd_right, analytic);
         }
         break;
         case FiniteDiffStrategy::FULL_FINITE_DIFF: