Fix 1417 again

regtest/basic/rt-make-settimestep-rounding/COLVAR.reference

@@ -0,0 +1,4 @@
+#! FIELDS time c
+ 20000.000000 1.000000
+#! FIELDS time c
+ 20000.000000 1.000000

regtest/basic/rt-make-settimestep-rounding/Makefile

@@ -0,0 +1 @@
+include ../../scripts/test.make

regtest/basic/rt-make-settimestep-rounding/config

@@ -0,0 +1 @@
+type=make

regtest/basic/rt-make-settimestep-rounding/main.cpp

@@ -0,0 +1,53 @@
+#include <vector>
+#include <fstream>
+#include "plumed/wrapper/Plumed.h"
+#include <iostream>
+
+using namespace PLMD;
+
+template<typename T>
+void run(){
+
+  auto natoms=10;
+  std::vector<T> masses;
+  std::vector<std::array<T,3>> positions;
+  std::vector<std::array<T,3>> forces;
+  T box[3][3];
+  T virial[3][3];
+
+  Plumed p;
+
+  p.cmd("setRealPrecision",int(sizeof(T)));
+  p.cmd("setNatoms",natoms);
+  p.cmd("setTimestep",(T)0.002);
+  p.cmd("init");
+
+  p.cmd("readInputLines",
+    "c: CONSTANT VALUE=1.0 \n"
+    "PRINT ARG=c FILE=COLVAR RESTART=YES\n"
+  );
+
+  // dummy settings, not really used
+  positions.resize(natoms);
+  masses.resize(natoms);
+  forces.resize(natoms);
+
+  for(unsigned i=0;i<natoms;i++) for(unsigned j=0;j<3;j++) positions[i][j]=0.0;
+  for(unsigned i=0;i<natoms;i++) for(unsigned j=0;j<3;j++) forces[i][j]=0.0;
+  for(unsigned i=0;i<natoms;i++) masses[i]=1.0;
+
+  p.cmd("setStep",10000000);
+  p.cmd("setMasses",&masses[0]);
+  p.cmd("setPositions",&positions[0][0]);
+  p.cmd("setForces",&forces[0][0]);
+
+  p.cmd("setBox",&box[0][0]);
+  p.cmd("setVirial",&virial[0][0]);
+  p.cmd("calc");
+
+}
+
+int main(){
+  run<double>();
+  run<float>();
+}

src/core/DataPassingObject.cpp

@@ -94,6 +94,17 @@ void DataPassingObjectTyped<T>::saveValueAsDouble( const TypesafePtr & val ) {
   bvalue=double(val.template get<T>());
 }
 
+template <>
+void DataPassingObjectTyped<float>::saveValueAsDouble( const TypesafePtr & val ) {
+  hasbackup=true;
+  bvalue=double(val.template get<float>());
+  // The following is to avoid extra digits in case the MD code uses floats
+  // e.g.: float f=0.002 when converted to double becomes 0.002000000094995
+  // To avoid this, we keep only up to 6 significant digits after first one
+  double magnitude=std::pow(10,std::floor(std::log10(bvalue)));
+  bvalue = std::round(bvalue/magnitude*1e6)/1e6*magnitude;
+}
+
 template <class T>
 void DataPassingObjectTyped<T>::setValuePointer( const TypesafePtr & val, const std::vector<unsigned>& shape, const bool& isconst ) {
   if( shape.size()==0 ) {

src/core/PlumedMain.cpp

@@ -737,14 +737,6 @@ void PlumedMain::cmd(std::string_view word,const TypesafePtr & val) {
         if( !ts->setValuePointer("timestep", val ) ) {
           plumed_error();
         }
-        // The following is to avoid extra digits in case the MD code uses floats
-        // e.g.: float f=0.002 when converted to double becomes 0.002000000094995
-        // To avoid this, we keep only up to 6 significant digits after first one
-        if( getRealPrecision()<=4 ) {
-          Value* tstepv = ts->copyOutput(0);
-          double magnitude=std::pow(10,std::floor(std::log10(tstepv->get())));
-          tstepv->set( std::round(tstepv->get()/magnitude*1e6)/1e6*magnitude );
-        }
         ts->updateUnits( passtools.get() );
       }
       break;