Adding constants for coincidence checking

Author: pshriwise

include/openmc/constants.h

@@ -51,6 +51,10 @@ constexpr double FP_PRECISION {1e-14};
 constexpr double FP_REL_PRECISION {1e-5};
 constexpr double FP_COINCIDENT {1e-12};
 
+// Coincidence tolerances
+constexpr double TORUS_TOL {1e-10};
+constexpr double RADIAL_MESH_TOL {1e-10};
+
 // Maximum number of random samples per history
 constexpr int MAX_SAMPLE {100000};
 

src/mesh.cpp

@@ -1088,7 +1088,7 @@ double CylindricalMesh::find_r_crossing(
   D = std::sqrt(D);
 
   // the solution -p - D is always smaller as -p + D : Check this one first
-  if (std::abs(c) <= 1e-10)
+  if (std::abs(c) <= RADIAL_MESH_TOL)
     return INFTY;
 
   if (-p - D > l)
@@ -1316,7 +1316,7 @@ double SphericalMesh::find_r_crossing(
   double c = r.dot(r) - r0 * r0;
   double D = p * p - c;
 
-  if (std::abs(c) <= 1e-10)
+  if (std::abs(c) <= RADIAL_MESH_TOL)
     return INFTY;
 
   if (D >= 0.0) {

src/surface.cpp

@@ -1044,7 +1044,7 @@ double torus_distance(double x1, double x2, double x3, double u1, double u2,
   // zero but possibly small and positive. A tolerance is set to discard that
   // zero.
   double distance = INFTY;
-  double cutoff = coincident ? 1e-10 : 0.0;
+  double cutoff = coincident ? TORUS_TOL : 0.0;
   for (int i = 0; i < 4; ++i) {
     if (roots[i].imag() == 0) {
       double root = roots[i].real();