Implemented updateParametersInContext() for seven more Force classes

openmmapi/src/CustomTorsionForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2010 Stanford University and the Authors.           *
+ * Portions copyright (c) 2010-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -113,3 +113,6 @@ map<string, double> CustomTorsionForceImpl::getDefaultParameters() {
     return parameters;
 }
 
+void CustomTorsionForceImpl::updateParametersInContext(ContextImpl& context) {
+    kernel.getAs<CalcCustomTorsionForceKernel>().copyParametersToContext(context, owner);
+}

openmmapi/src/HarmonicAngleForce.cpp

@@ -66,3 +66,7 @@ void HarmonicAngleForce::setAngleParameters(int index, int particle1, int partic
 ForceImpl* HarmonicAngleForce::createImpl() {
     return new HarmonicAngleForceImpl(*this);
 }
+
+void HarmonicAngleForce::updateParametersInContext(Context& context) {
+    dynamic_cast<HarmonicAngleForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
+}

openmmapi/src/HarmonicAngleForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -60,3 +60,7 @@ std::vector<std::string> HarmonicAngleForceImpl::getKernelNames() {
     names.push_back(CalcHarmonicAngleForceKernel::Name());
     return names;
 }
+
+void HarmonicAngleForceImpl::updateParametersInContext(ContextImpl& context) {
+    kernel.getAs<CalcHarmonicAngleForceKernel>().copyParametersToContext(context, owner);
+}

openmmapi/src/HarmonicBondForce.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -64,3 +64,7 @@ void HarmonicBondForce::setBondParameters(int index, int particle1, int particle
 ForceImpl* HarmonicBondForce::createImpl() {
     return new HarmonicBondForceImpl(*this);
 }
+
+void HarmonicBondForce::updateParametersInContext(Context& context) {
+    dynamic_cast<HarmonicBondForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
+}

openmmapi/src/HarmonicBondForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -70,3 +70,7 @@ vector<pair<int, int> > HarmonicBondForceImpl::getBondedParticles() const {
     }
     return bonds;
 }
+
+void HarmonicBondForceImpl::updateParametersInContext(ContextImpl& context) {
+    kernel.getAs<CalcHarmonicBondForceKernel>().copyParametersToContext(context, owner);
+}

openmmapi/src/PeriodicTorsionForce.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -70,3 +70,7 @@ void PeriodicTorsionForce::setTorsionParameters(int index, int particle1, int pa
 ForceImpl* PeriodicTorsionForce::createImpl() {
     return new PeriodicTorsionForceImpl(*this);
 }
+
+void PeriodicTorsionForce::updateParametersInContext(Context& context) {
+    dynamic_cast<PeriodicTorsionForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
+}

openmmapi/src/PeriodicTorsionForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -60,3 +60,7 @@ std::vector<std::string> PeriodicTorsionForceImpl::getKernelNames() {
     names.push_back(CalcPeriodicTorsionForceKernel::Name());
     return names;
 }
+
+void PeriodicTorsionForceImpl::updateParametersInContext(ContextImpl& context) {
+    kernel.getAs<CalcPeriodicTorsionForceKernel>().copyParametersToContext(context, owner);
+}

openmmapi/src/RBTorsionForce.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -76,3 +76,7 @@ void RBTorsionForce::setTorsionParameters(int index, int particle1, int particle
 ForceImpl* RBTorsionForce::createImpl() {
     return new RBTorsionForceImpl(*this);
 }
+
+void RBTorsionForce::updateParametersInContext(Context& context) {
+    dynamic_cast<RBTorsionForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context));
+}

openmmapi/src/RBTorsionForceImpl.cpp

@@ -6,7 +6,7 @@
  * Biological Structures at Stanford, funded under the NIH Roadmap for        *
  * Medical Research, grant U54 GM072970. See https://simtk.org.               *
  *                                                                            *
- * Portions copyright (c) 2008 Stanford University and the Authors.           *
+ * Portions copyright (c) 2008-2012 Stanford University and the Authors.      *
  * Authors: Peter Eastman                                                     *
  * Contributors:                                                              *
  *                                                                            *
@@ -60,3 +60,7 @@ std::vector<std::string> RBTorsionForceImpl::getKernelNames() {
     names.push_back(CalcRBTorsionForceKernel::Name());
     return names;
 }
+
+void RBTorsionForceImpl::updateParametersInContext(ContextImpl& context) {
+    kernel.getAs<CalcRBTorsionForceKernel>().copyParametersToContext(context, owner);
+}

platforms/cuda/src/CudaKernels.cpp

@@ -255,6 +255,10 @@ double CudaCalcHarmonicBondForceKernel::execute(ContextImpl& context, bool inclu
     return 0.0;
 }
 
+void CudaCalcHarmonicBondForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcCustomBondForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const CustomBondForce& force) : force(force) {
@@ -327,6 +331,10 @@ void CudaCalcCustomBondForceKernel::updateGlobalParams(ContextImpl& context) {
         SetCustomBondGlobalParams(globalParamValues);
 }
 
+void CudaCalcCustomBondForceKernel::copyParametersToContext(ContextImpl& context, const CustomBondForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcHarmonicAngleForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const HarmonicAngleForce& force) : force(force) {
@@ -380,6 +388,10 @@ double CudaCalcHarmonicAngleForceKernel::execute(ContextImpl& context, bool incl
     return 0.0;
 }
 
+void CudaCalcHarmonicAngleForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcCustomAngleForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const CustomAngleForce& force) : force(force) {
@@ -454,6 +466,10 @@ void CudaCalcCustomAngleForceKernel::updateGlobalParams(ContextImpl& context) {
         SetCustomAngleGlobalParams(globalParamValues);
 }
 
+void CudaCalcCustomAngleForceKernel::copyParametersToContext(ContextImpl& context, const CustomAngleForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcPeriodicTorsionForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const PeriodicTorsionForce& force) : force(force) {
@@ -510,6 +526,10 @@ double CudaCalcPeriodicTorsionForceKernel::execute(ContextImpl& context, bool in
     return 0.0;
 }
 
+void CudaCalcPeriodicTorsionForceKernel::copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcRBTorsionForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const RBTorsionForce& force) : force(force) {
@@ -572,6 +592,10 @@ double CudaCalcRBTorsionForceKernel::execute(ContextImpl& context, bool includeF
     return 0.0;
 }
 
+void CudaCalcRBTorsionForceKernel::copyParametersToContext(ContextImpl& context, const RBTorsionForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcCMAPTorsionForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const CMAPTorsionForce& force) : force(force) {
@@ -746,6 +770,10 @@ void CudaCalcCustomTorsionForceKernel::updateGlobalParams(ContextImpl& context)
         SetCustomTorsionGlobalParams(globalParamValues);
 }
 
+void CudaCalcCustomTorsionForceKernel::copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force) {
+    throw OpenMMException("CudaPlatform does not support copyParametersToContext");
+}
+
 class CudaCalcNonbondedForceKernel::ForceInfo : public CudaForceInfo {
 public:
     ForceInfo(const NonbondedForce& force) : force(force) {

platforms/cuda/src/CudaKernels.h

@@ -242,6 +242,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force);
 private:
     class ForceInfo;
     int numBonds;
@@ -274,6 +281,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomBondForce& force);
 private:
     class ForceInfo;
     void updateGlobalParams(ContextImpl& context);
@@ -308,6 +322,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force);
 private:
     class ForceInfo;
     int numAngles;
@@ -340,6 +361,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomAngleForce& force);
 private:
     class ForceInfo;
     void updateGlobalParams(ContextImpl& context);
@@ -374,6 +402,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the PeriodicTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force);
 private:
     class ForceInfo;
     int numTorsions;
@@ -405,6 +440,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the RBTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const RBTorsionForce& force);
 private:
     class ForceInfo;
     int numTorsions;
@@ -474,6 +516,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force);
 private:
     class ForceInfo;
     void updateGlobalParams(ContextImpl& context);

platforms/opencl/src/OpenCLKernels.cpp

@@ -351,6 +351,29 @@ double OpenCLCalcHarmonicBondForceKernel::execute(ContextImpl& context, bool inc
     return 0.0;
 }
 
+void OpenCLCalcHarmonicBondForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumBonds()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumBonds()/numContexts;
+    if (numBonds != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of bonds has changed");
+    
+    // Record the per-bond parameters.
+    
+    vector<mm_float2> paramVector(numBonds);
+    for (int i = 0; i < numBonds; i++) {
+        int atom1, atom2;
+        double length, k;
+        force.getBondParameters(startIndex+i, atom1, atom2, length, k);
+        paramVector[i] = mm_float2((cl_float) length, (cl_float) k);
+    }
+    params->upload(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLCustomBondForceInfo : public OpenCLForceInfo {
 public:
     OpenCLCustomBondForceInfo(const CustomBondForce& force) : OpenCLForceInfo(0), force(force) {
@@ -467,6 +490,31 @@ double OpenCLCalcCustomBondForceKernel::execute(ContextImpl& context, bool inclu
     return 0.0;
 }
 
+void OpenCLCalcCustomBondForceKernel::copyParametersToContext(ContextImpl& context, const CustomBondForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumBonds()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumBonds()/numContexts;
+    if (numBonds != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of bonds has changed");
+    
+    // Record the per-bond parameters.
+    
+    vector<vector<cl_float> > paramVector(numBonds);
+    vector<double> parameters;
+    for (int i = 0; i < numBonds; i++) {
+        int atom1, atom2;
+        force.getBondParameters(startIndex+i, atom1, atom2, parameters);
+        paramVector[i].resize(parameters.size());
+        for (int j = 0; j < (int) parameters.size(); j++)
+            paramVector[i][j] = (cl_float) parameters[j];
+    }
+    params->setParameterValues(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLHarmonicAngleForceInfo : public OpenCLForceInfo {
 public:
     OpenCLHarmonicAngleForceInfo(const HarmonicAngleForce& force) : OpenCLForceInfo(0), force(force) {
@@ -527,6 +575,29 @@ double OpenCLCalcHarmonicAngleForceKernel::execute(ContextImpl& context, bool in
     return 0.0;
 }
 
+void OpenCLCalcHarmonicAngleForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumAngles()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumAngles()/numContexts;
+    if (numAngles != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of angles has changed");
+    
+    // Record the per-angle parameters.
+    
+    vector<mm_float2> paramVector(numAngles);
+    for (int i = 0; i < numAngles; i++) {
+        int atom1, atom2, atom3;
+        double angle, k;
+        force.getAngleParameters(startIndex+i, atom1, atom2, atom3, angle, k);
+        paramVector[i] = mm_float2((cl_float) angle, (cl_float) k);
+    }
+    params->upload(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLCustomAngleForceInfo : public OpenCLForceInfo {
 public:
     OpenCLCustomAngleForceInfo(const CustomAngleForce& force) : OpenCLForceInfo(0), force(force) {
@@ -644,6 +715,31 @@ double OpenCLCalcCustomAngleForceKernel::execute(ContextImpl& context, bool incl
     return 0.0;
 }
 
+void OpenCLCalcCustomAngleForceKernel::copyParametersToContext(ContextImpl& context, const CustomAngleForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumAngles()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumAngles()/numContexts;
+    if (numAngles != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of angles has changed");
+    
+    // Record the per-angle parameters.
+    
+    vector<vector<cl_float> > paramVector(numAngles);
+    vector<double> parameters;
+    for (int i = 0; i < numAngles; i++) {
+        int atom1, atom2, atom3;
+        force.getAngleParameters(startIndex+i, atom1, atom2, atom3, parameters);
+        paramVector[i].resize(parameters.size());
+        for (int j = 0; j < (int) parameters.size(); j++)
+            paramVector[i][j] = (cl_float) parameters[j];
+    }
+    params->setParameterValues(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLPeriodicTorsionForceInfo : public OpenCLForceInfo {
 public:
     OpenCLPeriodicTorsionForceInfo(const PeriodicTorsionForce& force) : OpenCLForceInfo(0), force(force) {
@@ -692,7 +788,6 @@ void OpenCLCalcPeriodicTorsionForceKernel::initialize(const System& system, cons
         double phase, k;
         force.getTorsionParameters(startIndex+i, atoms[i][0], atoms[i][1], atoms[i][2], atoms[i][3], periodicity, phase, k);
         paramVector[i] = mm_float4((cl_float) k, (cl_float) phase, (cl_float) periodicity, 0.0f);
-
     }
     params->upload(paramVector);
     map<string, string> replacements;
@@ -706,6 +801,29 @@ double OpenCLCalcPeriodicTorsionForceKernel::execute(ContextImpl& context, bool
     return 0.0;
 }
 
+void OpenCLCalcPeriodicTorsionForceKernel::copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumTorsions()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumTorsions()/numContexts;
+    if (numTorsions != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of torsions has changed");
+    
+    // Record the per-torsion parameters.
+    
+    vector<mm_float4> paramVector(numTorsions);
+    for (int i = 0; i < numTorsions; i++) {
+        int atom1, atom2, atom3, atom4, periodicity;
+        double phase, k;
+        force.getTorsionParameters(startIndex+i, atom1, atom2, atom3, atom4, periodicity, phase, k);
+        paramVector[i] = mm_float4((cl_float) k, (cl_float) phase, (cl_float) periodicity, 0.0f);
+    }
+    params->upload(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLRBTorsionForceInfo : public OpenCLForceInfo {
 public:
     OpenCLRBTorsionForceInfo(const RBTorsionForce& force) : OpenCLForceInfo(0), force(force) {
@@ -767,6 +885,29 @@ double OpenCLCalcRBTorsionForceKernel::execute(ContextImpl& context, bool includ
     return 0.0;
 }
 
+void OpenCLCalcRBTorsionForceKernel::copyParametersToContext(ContextImpl& context, const RBTorsionForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumTorsions()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumTorsions()/numContexts;
+    if (numTorsions != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of torsions has changed");
+    
+    // Record the per-torsion parameters.
+    
+    vector<mm_float8> paramVector(numTorsions);
+    for (int i = 0; i < numTorsions; i++) {
+        int atom1, atom2, atom3, atom4;
+        double c0, c1, c2, c3, c4, c5;
+        force.getTorsionParameters(startIndex+i, atom1, atom2, atom3, atom4, c0, c1, c2, c3, c4, c5);
+        paramVector[i] = mm_float8((cl_float) c0, (cl_float) c1, (cl_float) c2, (cl_float) c3, (cl_float) c4, (cl_float) c5, 0.0f, 0.0f);
+    }
+    params->upload(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLCMAPTorsionForceInfo : public OpenCLForceInfo {
 public:
     OpenCLCMAPTorsionForceInfo(const CMAPTorsionForce& force) : OpenCLForceInfo(0), force(force) {
@@ -972,6 +1113,31 @@ double OpenCLCalcCustomTorsionForceKernel::execute(ContextImpl& context, bool in
     return 0.0;
 }
 
+void OpenCLCalcCustomTorsionForceKernel::copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force) {
+    int numContexts = cl.getPlatformData().contexts.size();
+    int startIndex = cl.getContextIndex()*force.getNumTorsions()/numContexts;
+    int endIndex = (cl.getContextIndex()+1)*force.getNumTorsions()/numContexts;
+    if (numTorsions != endIndex-startIndex)
+        throw OpenMMException("updateParametersInContext: The number of torsions has changed");
+    
+    // Record the per-torsion parameters.
+    
+    vector<vector<cl_float> > paramVector(numTorsions);
+    vector<double> parameters;
+    for (int i = 0; i < numTorsions; i++) {
+        int atom1, atom2, atom3, atom4;
+        force.getTorsionParameters(startIndex+i, atom1, atom2, atom3, atom4, parameters);
+        paramVector[i].resize(parameters.size());
+        for (int j = 0; j < (int) parameters.size(); j++)
+            paramVector[i][j] = (cl_float) parameters[j];
+    }
+    params->setParameterValues(paramVector);
+    
+    // Mark that the current reordering may be invalid.
+    
+    cl.invalidateMolecules();
+}
+
 class OpenCLNonbondedForceInfo : public OpenCLForceInfo {
 public:
     OpenCLNonbondedForceInfo(int requiredBuffers, const NonbondedForce& force) : OpenCLForceInfo(requiredBuffers), force(force) {

platforms/opencl/src/OpenCLKernels.h

@@ -243,6 +243,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force);
 private:
     int numBonds;
     bool hasInitializedKernel;
@@ -276,6 +283,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomBondForce& force);
 private:
     int numBonds;
     bool hasInitializedKernel;
@@ -312,6 +326,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force);
 private:
     int numAngles;
     bool hasInitializedKernel;
@@ -345,6 +366,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomAngleForce& force);
 private:
     int numAngles;
     bool hasInitializedKernel;
@@ -381,6 +409,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the PeriodicTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force);
 private:
     int numTorsions;
     bool hasInitializedKernel;
@@ -414,6 +449,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the RBTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const RBTorsionForce& force);
 private:
     int numTorsions;
     bool hasInitializedKernel;
@@ -482,6 +524,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force);
 private:
     int numTorsions;
     bool hasInitializedKernel;

platforms/opencl/src/OpenCLParallelKernels.cpp

@@ -234,6 +234,11 @@ double OpenCLParallelCalcHarmonicBondForceKernel::execute(ContextImpl& context,
     return 0.0;
 }
 
+void OpenCLParallelCalcHarmonicBondForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcCustomBondForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcCustomBondForceKernel& kernel, bool includeForce,
@@ -270,6 +275,11 @@ double OpenCLParallelCalcCustomBondForceKernel::execute(ContextImpl& context, bo
     return 0.0;
 }
 
+void OpenCLParallelCalcCustomBondForceKernel::copyParametersToContext(ContextImpl& context, const CustomBondForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcHarmonicAngleForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcHarmonicAngleForceKernel& kernel, bool includeForce,
@@ -306,6 +316,11 @@ double OpenCLParallelCalcHarmonicAngleForceKernel::execute(ContextImpl& context,
     return 0.0;
 }
 
+void OpenCLParallelCalcHarmonicAngleForceKernel::copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcCustomAngleForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcCustomAngleForceKernel& kernel, bool includeForce,
@@ -342,6 +357,11 @@ double OpenCLParallelCalcCustomAngleForceKernel::execute(ContextImpl& context, b
     return 0.0;
 }
 
+void OpenCLParallelCalcCustomAngleForceKernel::copyParametersToContext(ContextImpl& context, const CustomAngleForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcPeriodicTorsionForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcPeriodicTorsionForceKernel& kernel, bool includeForce,
@@ -378,6 +398,11 @@ double OpenCLParallelCalcPeriodicTorsionForceKernel::execute(ContextImpl& contex
     return 0.0;
 }
 
+void OpenCLParallelCalcPeriodicTorsionForceKernel::copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcRBTorsionForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcRBTorsionForceKernel& kernel, bool includeForce,
@@ -414,6 +439,11 @@ double OpenCLParallelCalcRBTorsionForceKernel::execute(ContextImpl& context, boo
     return 0.0;
 }
 
+void OpenCLParallelCalcRBTorsionForceKernel::copyParametersToContext(ContextImpl& context, const RBTorsionForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcCMAPTorsionForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcCMAPTorsionForceKernel& kernel, bool includeForce,
@@ -486,6 +516,11 @@ double OpenCLParallelCalcCustomTorsionForceKernel::execute(ContextImpl& context,
     return 0.0;
 }
 
+void OpenCLParallelCalcCustomTorsionForceKernel::copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force) {
+    for (int i = 0; i < (int) kernels.size(); i++)
+        getKernel(i).copyParametersToContext(context, force);
+}
+
 class OpenCLParallelCalcNonbondedForceKernel::Task : public OpenCLContext::WorkTask {
 public:
     Task(ContextImpl& context, OpenCLCalcNonbondedForceKernel& kernel, bool includeForce,

platforms/opencl/src/OpenCLParallelKernels.h

@@ -113,6 +113,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicBondForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;
@@ -144,6 +151,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomBondForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomBondForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;
@@ -175,6 +189,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the HarmonicAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const HarmonicAngleForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;
@@ -206,6 +227,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomAngleForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomAngleForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;
@@ -238,6 +266,13 @@ public:
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
     class Task;
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the PeriodicTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const PeriodicTorsionForce& force);
 private:
     OpenCLPlatform::PlatformData& data;
     std::vector<Kernel> kernels;
@@ -268,6 +303,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the RBTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const RBTorsionForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;
@@ -330,6 +372,13 @@ public:
      * @return the potential energy due to the force
      */
     double execute(ContextImpl& context, bool includeForces, bool includeEnergy);
+    /**
+     * Copy changed parameters over to a context.
+     *
+     * @param context    the context to copy parameters to
+     * @param force      the CustomTorsionForce to copy the parameters from
+     */
+    void copyParametersToContext(ContextImpl& context, const CustomTorsionForce& force);
 private:
     class Task;
     OpenCLPlatform::PlatformData& data;

platforms/opencl/tests/TestOpenCLCustomAngleForce.cpp

@@ -90,11 +90,36 @@ void testAngles() {
     init_gen_rand(0, sfmt);
 
     vector<Vec3> positions(4);
+    VerletIntegrator integrator1(0.01);
+    VerletIntegrator integrator2(0.01);
+    Context c1(customSystem, integrator1, platform);
+    Context c2(harmonicSystem, integrator2, platform);
     for (int i = 0; i < 10; i++) {
-        VerletIntegrator integrator1(0.01);
-        VerletIntegrator integrator2(0.01);
-        Context c1(customSystem, integrator1, platform);
-        Context c2(harmonicSystem, integrator2, platform);
+        for (int j = 0; j < (int) positions.size(); j++)
+            positions[j] = Vec3(5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt));
+        c1.setPositions(positions);
+        c2.setPositions(positions);
+        State s1 = c1.getState(State::Forces | State::Energy);
+        State s2 = c2.getState(State::Forces | State::Energy);
+        const vector<Vec3>& forces = s1.getForces();
+        for (int i = 0; i < customSystem.getNumParticles(); i++)
+            ASSERT_EQUAL_VEC(s1.getForces()[i], s2.getForces()[i], TOL);
+        ASSERT_EQUAL_TOL(s1.getPotentialEnergy(), s2.getPotentialEnergy(), TOL);
+    }
+    
+    // Try changing the angle parameters and make sure it's still correct.
+    
+    parameters[0] = 1.6;
+    parameters[1] = 0.9;
+    custom->setAngleParameters(0, 0, 1, 2, parameters);
+    parameters[0] = 2.1;
+    parameters[1] = 0.6;
+    custom->setAngleParameters(1, 1, 2, 3, parameters);
+    custom->updateParametersInContext(c1);
+    harmonic->setAngleParameters(0, 0, 1, 2, 1.6, 0.9);
+    harmonic->setAngleParameters(1, 1, 2, 3, 2.1, 0.6);
+    harmonic->updateParametersInContext(c2);
+    {
         for (int j = 0; j < (int) positions.size(); j++)
             positions[j] = Vec3(5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt));
         c1.setPositions(positions);

platforms/opencl/tests/TestOpenCLCustomBondForce.cpp

@@ -74,11 +74,31 @@ void testBonds() {
     positions[2] = Vec3(1, 0, 0);
     context.setPositions(positions);
     State state = context.getState(State::Forces | State::Energy);
-    const vector<Vec3>& forces = state.getForces();
-    ASSERT_EQUAL_VEC(Vec3(0, -0.8*0.5, 0), forces[0], TOL);
-    ASSERT_EQUAL_VEC(Vec3(0.7*0.2, 0, 0), forces[2], TOL);
-    ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
-    ASSERT_EQUAL_TOL(0.5*0.8*0.5*0.5 + 0.5*0.7*0.2*0.2, state.getPotentialEnergy(), TOL);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        ASSERT_EQUAL_VEC(Vec3(0, -0.8*0.5, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(0.7*0.2, 0, 0), forces[2], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
+        ASSERT_EQUAL_TOL(0.5*0.8*0.5*0.5 + 0.5*0.7*0.2*0.2, state.getPotentialEnergy(), TOL);
+    }
+    
+    // Try changing the bond parameters and make sure it's still correct.
+    
+    parameters[0] = 1.6;
+    parameters[1] = 0.9;
+    forceField->setBondParameters(0, 0, 1, parameters);
+    parameters[0] = 1.3;
+    parameters[1] = 0.8;
+    forceField->setBondParameters(1, 1, 2, parameters);
+    forceField->updateParametersInContext(context);
+    state = context.getState(State::Forces | State::Energy);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        ASSERT_EQUAL_VEC(Vec3(0, -0.9*0.4, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(0.8*0.3, 0, 0), forces[2], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
+        ASSERT_EQUAL_TOL(0.5*0.9*0.4*0.4 + 0.5*0.8*0.3*0.3, state.getPotentialEnergy(), TOL);
+    }
 }
 
 void testManyParameters() {

platforms/opencl/tests/TestOpenCLCustomTorsionForce.cpp

@@ -111,6 +111,31 @@ void testTorsions() {
             ASSERT_EQUAL_VEC(s1.getForces()[i], s2.getForces()[i], TOL);
         ASSERT_EQUAL_TOL(s1.getPotentialEnergy(), s2.getPotentialEnergy(), TOL);
     }
+    
+    // Try changing the torsion parameters and make sure it's still correct.
+    
+    parameters[0] = 1.6;
+    parameters[1] = 2;
+    custom->setTorsionParameters(0, 0, 1, 2, 3, parameters);
+    parameters[0] = 2.1;
+    parameters[1] = 3;
+    custom->setTorsionParameters(1, 1, 2, 3, 4, parameters);
+    custom->updateParametersInContext(c1);
+    periodic->setTorsionParameters(0, 0, 1, 2, 3, 2, 1.6, 0.5);
+    periodic->setTorsionParameters(1, 1, 2, 3, 4, 3, 2.1, 0.5);
+    periodic->updateParametersInContext(c2);
+    {
+        for (int j = 0; j < (int) positions.size(); j++)
+            positions[j] = Vec3(5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt), 5.0*genrand_real2(sfmt));
+        c1.setPositions(positions);
+        c2.setPositions(positions);
+        State s1 = c1.getState(State::Forces | State::Energy);
+        State s2 = c2.getState(State::Forces | State::Energy);
+        const vector<Vec3>& forces = s1.getForces();
+        for (int i = 0; i < customSystem.getNumParticles(); i++)
+            ASSERT_EQUAL_VEC(s1.getForces()[i], s2.getForces()[i], TOL);
+        ASSERT_EQUAL_TOL(s1.getPotentialEnergy(), s2.getPotentialEnergy(), TOL);
+    }
 }
 
 void testRange() {

platforms/opencl/tests/TestOpenCLHarmonicAngleForce.cpp

@@ -69,13 +69,33 @@ void testAngles() {
     positions[3] = Vec3(2, 1, 0);
     context.setPositions(positions);
     State state = context.getState(State::Forces | State::Energy);
-    const vector<Vec3>& forces = state.getForces();
-    double torque1 = 1.1*PI_M/6;
-    double torque2 = 1.2*PI_M/4;
-    ASSERT_EQUAL_VEC(Vec3(torque1, 0, 0), forces[0], TOL);
-    ASSERT_EQUAL_VEC(Vec3(-0.5*torque2, 0.5*torque2, 0), forces[3], TOL); // reduced by sqrt(2) due to the bond length, another sqrt(2) due to the angle
-    ASSERT_EQUAL_VEC(Vec3(forces[0][0]+forces[1][0]+forces[2][0]+forces[3][0], forces[0][1]+forces[1][1]+forces[2][1]+forces[3][1], forces[0][2]+forces[1][2]+forces[2][2]+forces[3][2]), Vec3(0, 0, 0), TOL);
-    ASSERT_EQUAL_TOL(0.5*1.1*(PI_M/6)*(PI_M/6) + 0.5*1.2*(PI_M/4)*(PI_M/4), state.getPotentialEnergy(), TOL);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        double torque1 = 1.1*PI_M/6;
+        double torque2 = 1.2*PI_M/4;
+        ASSERT_EQUAL_VEC(Vec3(torque1, 0, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-0.5*torque2, 0.5*torque2, 0), forces[3], TOL); // reduced by sqrt(2) due to the bond length, another sqrt(2) due to the angle
+        ASSERT_EQUAL_VEC(Vec3(forces[0][0]+forces[1][0]+forces[2][0]+forces[3][0], forces[0][1]+forces[1][1]+forces[2][1]+forces[3][1], forces[0][2]+forces[1][2]+forces[2][2]+forces[3][2]), Vec3(0, 0, 0), TOL);
+        ASSERT_EQUAL_TOL(0.5*1.1*(PI_M/6)*(PI_M/6) + 0.5*1.2*(PI_M/4)*(PI_M/4), state.getPotentialEnergy(), TOL);
+    }
+    
+    // Try changing the angle parameters and make sure it's still correct.
+    
+    forceField->setAngleParameters(0, 0, 1, 2, PI_M/3.1, 1.3);
+    forceField->setAngleParameters(1, 1, 2, 3, PI_M/2.1, 1.4);
+    forceField->updateParametersInContext(context);
+    state = context.getState(State::Forces | State::Energy);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        double dtheta1 = (PI_M/2)-(PI_M/3.1);
+        double dtheta2 = (3*PI_M/4)-(PI_M/2.1);
+        double torque1 = 1.3*dtheta1;
+        double torque2 = 1.4*dtheta2;
+        ASSERT_EQUAL_VEC(Vec3(torque1, 0, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-0.5*torque2, 0.5*torque2, 0), forces[3], TOL); // reduced by sqrt(2) due to the bond length, another sqrt(2) due to the angle
+        ASSERT_EQUAL_VEC(Vec3(forces[0][0]+forces[1][0]+forces[2][0]+forces[3][0], forces[0][1]+forces[1][1]+forces[2][1]+forces[3][1], forces[0][2]+forces[1][2]+forces[2][2]+forces[3][2]), Vec3(0, 0, 0), TOL);
+        ASSERT_EQUAL_TOL(0.5*1.3*dtheta1*dtheta1 + 0.5*1.4*dtheta2*dtheta2, state.getPotentialEnergy(), TOL);
+    }
 }
 
 void testParallelComputation() {

platforms/opencl/tests/TestOpenCLHarmonicBondForce.cpp

@@ -66,11 +66,27 @@ void testBonds() {
     positions[2] = Vec3(1, 0, 0);
     context.setPositions(positions);
     State state = context.getState(State::Forces | State::Energy);
-    const vector<Vec3>& forces = state.getForces();
-    ASSERT_EQUAL_VEC(Vec3(0, -0.8*0.5, 0), forces[0], TOL);
-    ASSERT_EQUAL_VEC(Vec3(0.7*0.2, 0, 0), forces[2], TOL);
-    ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
-    ASSERT_EQUAL_TOL(0.5*0.8*0.5*0.5 + 0.5*0.7*0.2*0.2, state.getPotentialEnergy(), TOL);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        ASSERT_EQUAL_VEC(Vec3(0, -0.8*0.5, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(0.7*0.2, 0, 0), forces[2], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
+        ASSERT_EQUAL_TOL(0.5*0.8*0.5*0.5 + 0.5*0.7*0.2*0.2, state.getPotentialEnergy(), TOL);
+    }
+    
+    // Try changing the bond parameters and make sure it's still correct.
+    
+    forceField->setBondParameters(0, 0, 1, 1.6, 0.9);
+    forceField->setBondParameters(1, 1, 2, 1.3, 0.8);
+    forceField->updateParametersInContext(context);
+    state = context.getState(State::Forces | State::Energy);
+    {
+        const vector<Vec3>& forces = state.getForces();
+        ASSERT_EQUAL_VEC(Vec3(0, -0.9*0.4, 0), forces[0], TOL);
+        ASSERT_EQUAL_VEC(Vec3(0.8*0.3, 0, 0), forces[2], TOL);
+        ASSERT_EQUAL_VEC(Vec3(-forces[0][0]-forces[2][0], -forces[0][1]-forces[2][1], -forces[0][2]-forces[2][2]), forces[1], TOL);
+        ASSERT_EQUAL_TOL(0.5*0.9*0.4*0.4 + 0.5*0.8*0.3*0.3, state.getPotentialEnergy(), TOL);
+    }
 }
 
 void testParallelComputation() {