Fixed inconsistency in computing kinetic energy (#3574)

11a1982a · Peter Eastman · GitHub · c8981916 · 11a1982a · 11a1982a
Unverified Commit 11a1982a authored Apr 15, 2022 by Peter Eastman Committed by GitHub Apr 15, 2022
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Showing with 11 additions and 8 deletions

platforms/cpu/src/CpuKernels.cpp platforms/cpu/src/CpuKernels.cpp +8 -6

platforms/reference/src/ReferenceKernels.cpp platforms/reference/src/ReferenceKernels.cpp +3 -2

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--- a/platforms/cpu/src/CpuKernels.cpp
+++ b/platforms/cpu/src/CpuKernels.cpp
@@ -124,10 +124,12 @@ static double computeShiftedKineticEnergy(ContextImpl& context, vector<double>&
    // Apply constraints to them.
+    if (timeShift != 0) {
        vector<double> inverseMasses(numParticles);
        for (int i = 0; i < numParticles; i++)
            inverseMasses[i] = (masses[i] == 0 ? 0 : 1/masses[i]);
        extractConstraints(context).applyToVelocities(posData, shiftedVel, inverseMasses, 1e-4);
+    }
    // Compute the kinetic energy.

--- a/platforms/reference/src/ReferenceKernels.cpp
+++ b/platforms/reference/src/ReferenceKernels.cpp
@@ -263,6 +263,7 @@ void ReferenceUpdateStateDataKernel::computeShiftedVelocities(ContextImpl& conte
    // Apply constraints to them.
+    if (timeShift != 0)
        extractConstraints(context).applyToVelocities(posData, velocities, inverseMasses, 1e-4);
 }