CarpetX: Implement minmod prolongation operator

CarpetX/param.ccl

@@ -433,7 +433,8 @@ KEYWORD prolongation_type "Prolongation type"
   "interpolate" :: "interpolate between data points"
   "conservative" :: "interpolate cell averages, ensuring conservation"
   "ddf" :: "interpolate in vertex centred and conserve (with one order lower) in cell centred directions"
-  "eno" :: "interpolate in vertex centred and ENO-conserve in cell centred directions"
+  "eno" :: "interpolate in vertex centred and minmod-conserve in cell centred directions"
+  "minmod" :: "interpolate in vertex centred and ENO-conserve in cell centred directions"
   "hermite" :: "Hermite-interpolate in vertex centred and conserve in cell centred directions"
   "natural" :: "interpolate in vertex centred and conserve in cell centred directions, using the same order"
   "poly-cons3lfb" :: "interpolate polynomially in vertex centred directions and conserve with 3rd order accuracy and a linear fallback in cell centred directions"

CarpetX/src/driver.cxx

@@ -541,6 +541,7 @@ amrex::Interpolater *get_interpolator(const std::array<int, dim> indextype) {
     conservative,
     ddf,
     eno,
+    minmod,
     hermite,
     natural,
     poly_cons3lfb,
@@ -555,6 +556,8 @@ amrex::Interpolater *get_interpolator(const std::array<int, dim> indextype) {
       return interp_t::ddf;
     else if (CCTK_EQUALS(prolongation_type, "eno"))
       return interp_t::eno;
+    else if (CCTK_EQUALS(prolongation_type, "minmod"))
+      return interp_t::minmod;
     else if (CCTK_EQUALS(prolongation_type, "hermite"))
       return interp_t::hermite;
     else if (CCTK_EQUALS(prolongation_type, "natural"))
@@ -894,6 +897,75 @@ amrex::Interpolater *get_interpolator(const std::array<int, dim> indextype) {
     }
     break;
 
+  case interp_t::minmod:
+
+    switch (prolongation_order) {
+
+    case 1:
+      switch ((indextype[0] << 2) | (indextype[1] << 1) | (indextype[2] << 0)) {
+      case 0b000:
+        return &prolongate_minmod_3d_rf2_c000_o1;
+      case 0b001:
+        return &prolongate_minmod_3d_rf2_c001_o1;
+      case 0b010:
+        return &prolongate_minmod_3d_rf2_c010_o1;
+      case 0b011:
+        return &prolongate_minmod_3d_rf2_c011_o1;
+      case 0b100:
+        return &prolongate_minmod_3d_rf2_c100_o1;
+      case 0b101:
+        return &prolongate_minmod_3d_rf2_c101_o1;
+      case 0b110:
+        return &prolongate_minmod_3d_rf2_c110_o1;
+      case 0b111:
+        return &prolongate_minmod_3d_rf2_c111_o1;
+      }
+      break;
+
+    case 3:
+      switch ((indextype[0] << 2) | (indextype[1] << 1) | (indextype[2] << 0)) {
+      case 0b000:
+        return &prolongate_minmod_3d_rf2_c000_o3;
+      case 0b001:
+        return &prolongate_minmod_3d_rf2_c001_o3;
+      case 0b010:
+        return &prolongate_minmod_3d_rf2_c010_o3;
+      case 0b011:
+        return &prolongate_minmod_3d_rf2_c011_o3;
+      case 0b100:
+        return &prolongate_minmod_3d_rf2_c100_o3;
+      case 0b101:
+        return &prolongate_minmod_3d_rf2_c101_o3;
+      case 0b110:
+        return &prolongate_minmod_3d_rf2_c110_o3;
+      case 0b111:
+        return &prolongate_minmod_3d_rf2_c111_o3;
+      }
+      break;
+
+    case 5:
+      switch ((indextype[0] << 2) | (indextype[1] << 1) | (indextype[2] << 0)) {
+      case 0b000:
+        return &prolongate_minmod_3d_rf2_c000_o5;
+      case 0b001:
+        return &prolongate_minmod_3d_rf2_c001_o5;
+      case 0b010:
+        return &prolongate_minmod_3d_rf2_c010_o5;
+      case 0b011:
+        return &prolongate_minmod_3d_rf2_c011_o5;
+      case 0b100:
+        return &prolongate_minmod_3d_rf2_c100_o5;
+      case 0b101:
+        return &prolongate_minmod_3d_rf2_c101_o5;
+      case 0b110:
+        return &prolongate_minmod_3d_rf2_c110_o5;
+      case 0b111:
+        return &prolongate_minmod_3d_rf2_c111_o5;
+      }
+      break;
+    }
+    break;
+
   case interp_t::hermite:
 
     switch (prolongation_order) {

CarpetX/src/make.code.defn

@@ -47,6 +47,7 @@ SRCS =							\
 	prolongate_3d_rf2_impl_ddf.cxx			\
 	prolongate_3d_rf2_impl_eno.cxx			\
 	prolongate_3d_rf2_impl_hermite.cxx		\
+	prolongate_3d_rf2_impl_minmod.cxx		\
 	prolongate_3d_rf2_impl_natural.cxx		\
 	prolongate_3d_rf2_impl_poly.cxx			\
 	prolongate_3d_rf2_impl_poly_cons3lfb.cxx	\

CarpetX/src/prolongate_3d_rf2.cxx

@@ -25,6 +25,8 @@ std::ostream &operator<<(std::ostream &os, const interpolation_t intp) {
     return os << "cons";
   case interpolation_t::eno:
     return os << "eno";
+  case interpolation_t::minmod:
+    return os << "minmod";
   }
   assert(false);
 }

CarpetX/src/prolongate_3d_rf2.hxx

@@ -15,12 +15,13 @@ std::ostream &operator<<(std::ostream &os, centering_t cent);
 constexpr auto VC = centering_t::vertex;
 constexpr auto CC = centering_t::cell;
 
-enum class interpolation_t { poly, hermite, cons, eno };
+enum class interpolation_t { poly, hermite, cons, eno, minmod };
 std::ostream &operator<<(std::ostream &os, interpolation_t cent);
 constexpr auto POLY = interpolation_t::poly;
 constexpr auto HERMITE = interpolation_t::hermite;
 constexpr auto CONS = interpolation_t::cons;
 constexpr auto ENO = interpolation_t::eno;
+constexpr auto MINMOD = interpolation_t::minmod;
 
 enum class fallback_t { none, linear };
 std::ostream &operator<<(std::ostream &os, fallback_t fb);
@@ -39,17 +40,22 @@ class prolongate_3d_rf2 final : public amrex::Interpolater {
 
   // Conservative must be one of the possible choices
   static_assert(INTPI == POLY || INTPI == HERMITE || INTPI == CONS ||
-                INTPI == ENO);
+                INTPI == ENO || INTPI == MINMOD);
   static_assert(INTPJ == POLY || INTPJ == HERMITE || INTPJ == CONS ||
-                INTPJ == ENO);
+                INTPJ == ENO || INTPJ == MINMOD);
   static_assert(INTPK == POLY || INTPK == HERMITE || INTPK == CONS ||
-                INTPK == ENO);
+                INTPK == ENO || INTPK == MINMOD);
 
   // Order must be nonnegative
   static_assert(ORDERI >= 0);
   static_assert(ORDERJ >= 0);
   static_assert(ORDERK >= 0);
 
+  // Minmod is always linear
+  static_assert(INTPI == MINMOD ? ORDERI == 1 : true);
+  static_assert(INTPJ == MINMOD ? ORDERJ == 1 : true);
+  static_assert(INTPK == MINMOD ? ORDERK == 1 : true);
+
   // Fallback must be one of the possible choices
   static_assert(FB == FB_NONE || FB == FB_LINEAR);
 
@@ -401,6 +407,59 @@ extern prolongate_3d_rf2<CC, CC, VC, ENO, ENO, POLY, 2, 2, 5, FB_NONE>
 extern prolongate_3d_rf2<CC, CC, CC, ENO, ENO, ENO, 2, 2, 2, FB_NONE>
     prolongate_eno_3d_rf2_c111_o5;
 
+// Minmod (tensor product) interpolation
+
+extern prolongate_3d_rf2<VC, VC, VC, POLY, POLY, POLY, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c000_o1;
+extern prolongate_3d_rf2<VC, VC, CC, POLY, POLY, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c001_o1;
+extern prolongate_3d_rf2<VC, CC, VC, POLY, MINMOD, POLY, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c010_o1;
+extern prolongate_3d_rf2<VC, CC, CC, POLY, MINMOD, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c011_o1;
+extern prolongate_3d_rf2<CC, VC, VC, MINMOD, POLY, POLY, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c100_o1;
+extern prolongate_3d_rf2<CC, VC, CC, MINMOD, POLY, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c101_o1;
+extern prolongate_3d_rf2<CC, CC, VC, MINMOD, MINMOD, POLY, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c110_o1;
+extern prolongate_3d_rf2<CC, CC, CC, MINMOD, MINMOD, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c111_o1;
+
+extern prolongate_3d_rf2<VC, VC, VC, POLY, POLY, POLY, 3, 3, 3, FB_NONE>
+    prolongate_minmod_3d_rf2_c000_o3;
+extern prolongate_3d_rf2<VC, VC, CC, POLY, POLY, MINMOD, 3, 3, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c001_o3;
+extern prolongate_3d_rf2<VC, CC, VC, POLY, MINMOD, POLY, 3, 1, 3, FB_NONE>
+    prolongate_minmod_3d_rf2_c010_o3;
+extern prolongate_3d_rf2<VC, CC, CC, POLY, MINMOD, MINMOD, 3, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c011_o3;
+extern prolongate_3d_rf2<CC, VC, VC, MINMOD, POLY, POLY, 1, 3, 3, FB_NONE>
+    prolongate_minmod_3d_rf2_c100_o3;
+extern prolongate_3d_rf2<CC, VC, CC, MINMOD, POLY, MINMOD, 1, 3, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c101_o3;
+extern prolongate_3d_rf2<CC, CC, VC, MINMOD, MINMOD, POLY, 1, 1, 3, FB_NONE>
+    prolongate_minmod_3d_rf2_c110_o3;
+extern prolongate_3d_rf2<CC, CC, CC, MINMOD, MINMOD, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c111_o3;
+
+extern prolongate_3d_rf2<VC, VC, VC, POLY, POLY, POLY, 5, 5, 5, FB_NONE>
+    prolongate_minmod_3d_rf2_c000_o5;
+extern prolongate_3d_rf2<VC, VC, CC, POLY, POLY, MINMOD, 5, 5, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c001_o5;
+extern prolongate_3d_rf2<VC, CC, VC, POLY, MINMOD, POLY, 5, 1, 5, FB_NONE>
+    prolongate_minmod_3d_rf2_c010_o5;
+extern prolongate_3d_rf2<VC, CC, CC, POLY, MINMOD, MINMOD, 5, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c011_o5;
+extern prolongate_3d_rf2<CC, VC, VC, MINMOD, POLY, POLY, 1, 5, 5, FB_NONE>
+    prolongate_minmod_3d_rf2_c100_o5;
+extern prolongate_3d_rf2<CC, VC, CC, MINMOD, POLY, MINMOD, 1, 5, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c101_o5;
+extern prolongate_3d_rf2<CC, CC, VC, MINMOD, MINMOD, POLY, 1, 1, 5, FB_NONE>
+    prolongate_minmod_3d_rf2_c110_o5;
+extern prolongate_3d_rf2<CC, CC, CC, MINMOD, MINMOD, MINMOD, 1, 1, 1, FB_NONE>
+    prolongate_minmod_3d_rf2_c111_o5;
+
 // Hermite interpolation
 
 extern prolongate_3d_rf2<VC, VC, VC, HERMITE, HERMITE, HERMITE, 1, 1, 1,