Re-organise time level handling

Store the current Cactus time (and not a fake Carpet time) in the th
"time hiearchy".  This removes the now redundant "leveltimes" data
structure in Carpet.

Add past time levels to th, so that it can store the time for past
time levels instead of assuming the time step size is constant.  This
allows changing the time step size during evolution.

Share the time hierarchy between all maps, instead of having one time
hierarchy per map.

Simplify the time level cycling and time stepping code used during
evolution.

Improve structure of the code that loops over time levels for certain
schedule bins.  Introduce a new Carpet variable "timelevel", similar
to "reflevel".

This also makes it possible to avoid time interpolation for the past
time levels during regridding.  The past time levels of the fine grid
then remain aligned (in time) with the past time levels of the coarse
grid.  This is controlled by a new parameter
"time_interpolation_during_regridding", which defaults to "yes" for
backwards compatibility.

Simplify the three time level initialisation.  Instead of initialising
all three time levels by taking altogether three time steps (forwards
and backwards), initialise only one past time level by taking one time
step backwards.  The remaining time level is initialised during the
first time step of the evolution, which begins by cycling time levels,
which drops the non-initialised last time level anyway.

Update Carpet and the mode handling correspondingly.

Update the CarpetIOHDF5 checkpoint format correspondingly.

Update CarpetInterp, CarpetReduce, and CarpetRegrid2 correspondingly.

Update CarpetJacobi and CarpetMG correspondingly.

1 files changed, 118 insertions, 22 deletions

diff --git a/Carpet/CarpetLib/src/th.cc b/Carpet/CarpetLib/src/th.cc
index dd441e455..bed473245 100644
--- a/Carpet/CarpetLib/src/th.cc
+++ b/Carpet/CarpetLib/src/th.cc
@@ -19,8 +19,10 @@ list<th*> th::allth;
 
 
 // Constructors
-th::th (gh& h_, const vector<int> & reffacts_, const CCTK_REAL basedelta)
-  : h(h_), reffacts(reffacts_), delta(basedelta)
+th::th (gh& h_, int const timelevels_, vector<int> const& reffacts_,
+        bool const time_interpolation_during_regridding_)
+  : h(h_), timelevels(timelevels_), reffacts(reffacts_),
+    time_interpolation_during_regridding (time_interpolation_during_regridding_)
 {
   assert (reffacts.size() >= 1);
   assert (reffacts.front() == 1);
@@ -42,6 +44,9 @@ th::~th ()
 // Modifiers
 void th::regrid ()
 {
+  CCTK_REAL const basetime  = 0.0;
+  CCTK_REAL const basedelta = 1.0;
+  
   const int old_mglevels = times.size();
   times.resize(h.mglevels());
   deltas.resize(h.mglevels());
@@ -50,17 +55,64 @@ void th::regrid ()
     times.AT(ml).resize(h.reflevels());
     deltas.AT(ml).resize(h.reflevels());
     for (int rl=0; rl<h.reflevels(); ++rl) {
+      if (ml==0) {
+	deltas.AT(ml).AT(rl) = basedelta / reffacts.AT(rl);
+      } else {
+	deltas.AT(ml).AT(rl) = deltas.AT(ml-1).AT(rl) * h.mgfact;
+      }
       if (old_mglevels==0) {
-        times.AT(ml).AT(rl) = 0;
+        times.AT(ml).AT(rl).resize(timelevels);
+        for (int tl=0; tl<timelevels; ++tl) {
+          times.AT(ml).AT(rl).AT(tl) = basetime - tl * deltas.AT(ml).AT(rl);
+        }
       } else if (rl < old_reflevels) {
         // do nothing
+      } else if (rl == 0) {
+        assert (0);
+        times.AT(ml).AT(rl).resize(timelevels);
+        for (int tl=0; tl<timelevels; ++tl) {
+          times.AT(ml).AT(rl).AT(tl) = basetime - tl * deltas.AT(ml).AT(rl);
+        }
       } else {
-        times.AT(ml).AT(rl) = times.AT(ml).AT(rl-1);
+        if (time_interpolation_during_regridding) {
+#warning "We probably don't want to do this, but it is nice for compatibility"
+          times.AT(ml).AT(rl).resize(timelevels);
+          for (int tl=0; tl<timelevels; ++tl) {
+            // linear interpolation between the two surrounding coarse
+            // grid times
+            assert (reffacts.AT(rl) % reffacts.AT(rl-1) == 0);
+            int const rf = reffacts.AT(rl) / reffacts.AT(rl-1);
+            int const ctl = tl / rf;
+            int const mtl = tl % rf;
+            if (mtl == 0) {
+              times.AT(ml).AT(rl).AT(tl) = times.AT(ml).AT(rl-1).AT(ctl);
+            } else {
+              assert (ctl+1<timelevels);
+              CCTK_REAL const alpha = (CCTK_REAL)mtl / rf;
+              assert (alpha>0 and alpha<1);
+              times.AT(ml).AT(rl).AT(tl) =
+                (1-alpha) * times.AT(ml).AT(rl-1).AT(ctl  ) +
+                (  alpha) * times.AT(ml).AT(rl-1).AT(ctl+1);
+            }
+          }
+        } else {
+          times.AT(ml).AT(rl) = times.AT(ml).AT(rl-1);
+        }
       }
-      if (ml==0) {
-	deltas.AT(ml).AT(rl) = delta / reffacts.AT(rl);
-      } else {
-	deltas.AT(ml).AT(rl) = deltas.AT(ml-1).AT(rl) * h.mgfact;
+    }
+  }
+  for (int ml=0; ml<h.mglevels(); ++ml) {
+    for (int rl=0; rl<h.reflevels(); ++rl) {
+      for (int tl=1; tl<timelevels; ++tl) {
+        assert (times.AT(ml).AT(rl).AT(tl) < times.AT(ml).AT(rl).AT(tl-1));
+      }
+    }
+  }
+  for (int ml=0; ml<h.mglevels(); ++ml) {
+    for (int rl=0; rl<h.reflevels(); ++rl) {
+      // assert (isfinite(deltas.AT(ml).AT(rl)));
+      for (int tl=0; tl<timelevels; ++tl) {
+        // assert (isfinite(times.AT(ml).AT(rl).AT(tl)));
       }
     }
   }
@@ -72,6 +124,37 @@ void th::regrid_free ()
 
 
 
+void th::advance_time (int const ml, int const rl)
+{
+  for (int tl=timelevels-1; tl>0; --tl) {
+    set_time (ml,rl,tl, get_time(ml,rl,tl-1));
+  }
+  set_time (ml,rl,0, get_time(ml,rl,0) + get_delta(ml,rl));
+}
+
+void th::retreat_time (int const ml, int const rl)
+{
+  CCTK_REAL const t = get_time(ml,rl,0);
+  for (int tl=0; tl<timelevels-1; ++tl) {
+    set_time (ml,rl,tl, get_time(ml,rl,tl+1));
+  }
+  set_time (ml,rl,timelevels-1, t);
+}
+
+void th::flip_timelevels (int const ml, int const rl)
+{
+  for (int tl=1; tl<(timelevels+1)/2; ++tl) {
+    int const tl2 = timelevels - tl;
+    CCTK_REAL const t  = get_time(ml,rl,tl );
+    CCTK_REAL const t2 = get_time(ml,rl,tl2);
+    set_time (ml,rl,tl ,t2);
+    set_time (ml,rl,tl2,t );
+  }
+  set_delta (ml,rl, -get_delta(ml,rl));
+}
+
+
+
 // Memory usage
 size_t
 th::
@@ -80,7 +163,6 @@ memory ()
 {
   return
     memoryof (reffacts) +
-    memoryof (delta) +
     memoryof (times) +
     memoryof (deltas);
 }
@@ -100,19 +182,33 @@ allmemory ()
 
 
 
+// Input
+istream& th::input (istream& is)
+{
+  skipws (is);
+  consume (is, "th:{");
+  consume (is, "timelevels=");
+  is >> timelevels;
+  consume (is, ",");
+  consume (is, "reffacts=");
+  is >> reffacts;
+  consume (is, ",");
+  consume (is, "times=");
+  is >> times;
+  consume (is, ",");
+  consume (is, "deltas=");
+  is >> deltas;
+  consume (is, "}");
+  return is;
+}
+
 // Output
-void th::output (ostream& os) const
+ostream& th::output (ostream& os) const
 {
-  os << "th:"
-     << "times={";
-  const char * sep = "";
-  for (int ml=0; ml<h.mglevels(); ++ml) {
-    for (int rl=0; rl<h.reflevels(); ++rl) {
-      os << sep
-         << ml << ":" << rl << ":"
-	 << times.AT(ml).AT(rl) << "(" << deltas.AT(ml).AT(rl) << ")";
-      sep = ",";
-    }
-  }
-  os << "}";
+  os << "th:{"
+     << "timelevels=" << timelevels << ","
+     << "reffacts=" << reffacts << ","
+     << "times=" << times << ","
+     << "deltas=" << deltas << "}";
+  return os;
 }