Add soft equivalence

src/globals.cpp

@@ -29,11 +29,10 @@ namespace Globals {
 
 int nghost;
 
-bool is_restart;
-
 // all of these global variables are set at the start of main():
 int my_rank; // MPI rank of this process
 int nranks;  // total number of MPI ranks
+bool is_restart; // Whether this simulation is restarted from a checkpoint file
 
 // sparse configuration values that are needed in various places
 SparseConfig sparse_config;

src/utils/robust.hpp

@@ -60,6 +60,24 @@ KOKKOS_INLINE_FUNCTION auto ratio(const A &a, const B &b) {
   const B sgn = b >= 0 ? 1 : -1;
   return a / (b + sgn * SMALL<B>());
 }
+
+KOKKOS_FORCEINLINE_FUNCTION
+bool soft_equiv(const Real &val, const Real &ref,
+                const Real eps = 10. * std::numeric_limits<Real>::epsilon(),
+                const bool pass_on_small = true) {
+  if (std::fabs(val - ref) < precision * fabs(ref)) {
+    // Return true equivalence if value and reference differ by less than precision
+    return true;
+  } else {
+    if (std::fabs(ref) < std::numeric_limits<Real>::min() && pass_on_small) {
+      // Optionally return true if reference value is close to zero
+      return true;
+    } else {
+      return false;
+    }
+  }
+}
+
 } // namespace robust
 } // namespace parthenon
 #endif // UTILS_ROBUST_HPP_