Added testing for the O(4) symmetric potentials.

src/bounce_solution/action_calculation.cpp

@@ -474,14 +474,14 @@
       ss << rho_up << "\t" << l << "\t" << dVdl << "\t" << d2Vdl2 << "\n";
       BSMPT::Logger::Write(BSMPT::LoggingLevel::BounceDetailed, ss.str());
       ss.str(std::string());
-      if (l0 == l0 + (l - l0) / 10.)
+      if (abs((l - l0) / Spline.L) < 1e-10)
       {
         // Maximum numerical precision reached.
         StateOfBounceActionInt = ActionStatus::Integration1DFailed;
         // Abort calculation
         return {0, 0, 0};
       }
       return (ExactSolutionLin(l0, l0 + (l - l0) / 10., dVdl, d2Vdl2));
     }
   }
   else
@@ -585,8 +585,12 @@
   if (not ExactSolutionThreshold.has_value())
     return ExactSolutionLin(l0, l, dVdl, d2Vdl2);
 
-  if (dVdl <= -1e-3)
+  if (dVdl <= 0)
   {
+    // Assume negative grad is numerical error if close to the true minimum
+    if (l0_minus_lmin / Spline.L < 1e-2) return ExactSolutionFromMinimum(l);
+    // If we are not close to the minimum then probably l0 in not a solution as
+    // it will roll backwards
     ss << " \n l = " << l0 << std::endl;
     ss << " dVdl = " << dVdl << std::endl;
     ss << " d2Vd2l = " << d2Vdl2 << std::endl;

src/utility/utility.cpp

@@ -88,8 +88,8 @@ double Li2(const double &x)
   if (x < -1) return -pow(M_PI, 2) / 6. - pow(log(-x), 2) / 2. - Li2(1. / x);
   if (x < 0) return 1 / 2. * Li2(-x * -x) - Li2(-x);
   if (x > 0.5) return pow(M_PI, 2) / 6. - log(x) * log(1 - x) - Li2(1 - x);
-  double sum = 1e-100;
-  for (int k = 1; k <= 1e5; k++)
+  double sum = x;                // k = 1 element of the sum
+  for (int k = 2; k <= 1e5; k++) // Sum starts at k = 2
   {
     if (abs((pow(x, k) / pow(k, 2.)) / sum) < 1e-10)
     {