add logic to rerun command to trigger dumps on expected steps or time

src/output.cpp

@@ -545,11 +545,9 @@ void Output::calculate_next_dump(int which, int idump, bigint ntimestep)
       // if delta is too small to reach next timestep, use multiple of delta
 
       if (nextdump == ntimestep) {
-        double tnext = update->atime +
-          (ntimestep+1 - update->atimestep) * update->dt;
-        int multiple = static_cast<int>
-          ((tnext - nexttime) / every_time_dump[idump]);
-        nexttime = nexttime + (multiple+1)*every_time_dump[idump];
+        double tnext = update->atime + (ntimestep + 1 - update->atimestep) * update->dt;
+        int multiple = static_cast<int>((tnext - nexttime) / every_time_dump[idump]);
+        nexttime = nexttime + (multiple + 1) * every_time_dump[idump];
         nextdump = ntimestep +
           static_cast<bigint> ((nexttime - tcurrent - EPSDT*update->dt) / update->dt) + 1;
       }

src/rerun.cpp

@@ -17,17 +17,20 @@
 #include "domain.h"
 #include "error.h"
 #include "finish.h"
+#include "input.h"
 #include "integrate.h"
 #include "modify.h"
 #include "output.h"
 #include "read_dump.h"
 #include "timer.h"
 #include "update.h"
+#include "variable.h"
 
 #include <cstring>
 
 using namespace LAMMPS_NS;
 
+#define EPSDT 1.0e-6
 /* ---------------------------------------------------------------------- */
 
 Rerun::Rerun(LAMMPS *lmp) : Command(lmp) {}
@@ -165,6 +168,78 @@ void Rerun::command(int narg, char **arg)
     modify->init();
     update->integrate->setup_minimal(1);
     modify->end_of_step();
+
+    // fix up the "next_dump" settings for dumps if the sequence differs from what is read in
+
+    for (int idump = 0; idump < output->ndump; ++idump) {
+      // dumps triggered by timestep
+      if (output->mode_dump[idump] == 0) {
+        // rerun has advanced the timestep faster than the dump expected so we need to catch it up
+        if (output->next_dump[idump] < ntimestep) {
+          // equidistant dumps
+          if (output->every_dump[idump]) {
+            // if current step compatible with dump frequency, adjust next_dump setting for dump
+            if (ntimestep % output->every_dump[idump] == 0) output->next_dump[idump] = ntimestep;
+          } else {
+            // next dump is determined by variable.
+            // advance next timestep computation from variable until it is equal or larger
+            // than the current dump timestep; trigger dump only if equal.
+            bigint savedstep = update->ntimestep;
+            update->ntimestep = output->next_dump[idump];
+            bigint nextdump;
+            do {
+              nextdump = (bigint) input->variable->compute_equal(output->ivar_dump[idump]);
+              update->ntimestep = nextdump;
+            } while (nextdump < ntimestep);
+            output->next_dump[idump] = nextdump;
+            update->ntimestep = savedstep;
+          }
+        }
+      } else {
+        // dumps triggered by time
+        double tcurrent = update->atime + (ntimestep - update->atimestep) * update->dt;
+        // rerun time has moved beyond expected time for dump so we need to catch it up
+        if (output->next_time_dump[idump] < tcurrent) {
+          // equidistant dumps in time
+          if (output->every_time_dump[idump] > 0.0) {
+            // trigger dump if current time is within +/- half a timestep of the every interval
+            double every = output->every_time_dump[idump];
+            double rest = fabs(tcurrent/every - round(tcurrent/every)) * every/update->dt;
+            if (rest < 0.5) {
+              output->next_dump[idump] = ntimestep;
+              output->next_time_dump[idump] = tcurrent;
+            } else {
+              double nexttime = (floor(tcurrent/every) + 1.0) * every;
+              output->next_dump[idump] = update->ntimestep
+                + (bigint) ((nexttime - (update->atime + (update->ntimestep - update->atimestep) *
+                                         update->dt) - EPSDT*update->dt) / update->dt) + 1;
+              output->next_time_dump[idump] = nexttime;
+            }
+          } else {
+            // next dump time is determined by variable.
+            // advance next time computation from variable until is is equal or larger
+            // than the current time/timestep
+            bigint savedstep = update->ntimestep;
+            update->ntimestep = output->next_dump[idump];
+            double nexttime = output->next_time_dump[idump];
+            bigint nextstep = output->next_dump[idump];
+            while (nextstep < ntimestep) {
+              nexttime = input->variable->compute_equal(output->ivar_dump[idump]);
+              nextstep = update->ntimestep
+                + (bigint) ((nexttime - (update->atime + (update->ntimestep - update->atimestep) *
+                                         update->dt) - EPSDT*update->dt) / update->dt) + 1;
+              update->ntimestep = nextstep;
+            };
+            if (ntimestep > 0) {
+              output->next_time_dump[idump] = nexttime;
+              output->next_dump[idump] = nextstep;
+            }
+            update->ntimestep = savedstep;
+          }
+        }
+      }
+    }
+
     output->next_dump_any = ntimestep;
     if (firstflag) output->setup();
     else if (output->next) output->write(ntimestep);
@@ -172,7 +247,7 @@ void Rerun::command(int narg, char **arg)
     firstflag = 0;
     ntimestep = rd->next(ntimestep,last,nevery,nskip);
     if (stopflag && ntimestep > stop)
-      error->all(FLERR,"Read rerun dump file timestep > specified stop");
+      error->all(FLERR,"Read rerun dump file timestep {} > specified stop {}", ntimestep, stop);
     if (ntimestep < 0) break;
   }