fd -> fd_centered

Author: Huangzizhou

src/polysolve/nonlinear/Solver.cpp

@@ -598,18 +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, fd_left, fd_right, 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, fd_left, fd_right, 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: