Fixed potential out of range index (#2960)

platforms/cuda/src/CudaKernels.cpp

@@ -1014,7 +1014,7 @@ void CudaCalcNonbondedForceKernel::initialize(const System& system, const Nonbon
                         }
                         for (int i = 0; i < ndata; i++)
                             if (moduli[i] < 1.0e-7)
-                                moduli[i] = (moduli[i-1]+moduli[i+1])*0.5;
+                                moduli[i] = (moduli[(i-1+ndata)%ndata]+moduli[(i+1)%ndata])*0.5;
                         if (dim == 0)
                             xmoduli->upload(moduli, true);
                         else if (dim == 1)

platforms/opencl/src/OpenCLKernels.cpp

@@ -963,7 +963,7 @@ void OpenCLCalcNonbondedForceKernel::initialize(const System& system, const Nonb
                         for (int i = 0; i < ndata; i++)
                         {
                             if (moduli[i] < 1.0e-7)
-                                moduli[i] = (moduli[i-1]+moduli[i+1])*0.5f;
+                                moduli[i] = (moduli[(i-1+ndata)%ndata]+moduli[(i+1)%ndata])*0.5;
                         }
                         if (dim == 0)
                             xmoduli->upload(moduli, true);

platforms/reference/src/SimTKReference/ReferencePME.cpp

@@ -181,7 +181,7 @@ pme_calculate_bsplines_moduli(pme_t pme)
         {
             if (pme->bsplines_moduli[d][i]<1.0e-7)
             {
-                pme->bsplines_moduli[d][i]=(pme->bsplines_moduli[d][i-1]+pme->bsplines_moduli[d][i+1])/2;
+                pme->bsplines_moduli[d][i]=(pme->bsplines_moduli[d][(i-1+ndata)%ndata]+pme->bsplines_moduli[d][(i+1)%ndata])/2;
             }
         }
     }

plugins/cpupme/src/CpuPmeKernels.cpp

@@ -520,7 +520,7 @@ void CpuCalcPmeReciprocalForceKernel::initialize(int xsize, int ysize, int zsize
         }
         for (int i = 0; i < ndata; i++)
             if (moduli[i] < 1.0e-7f)
-                moduli[i] = (moduli[i-1]+moduli[i+1])*0.5f;
+                moduli[i] = (moduli[(i-1+ndata)%ndata]+moduli[(i+1)%ndata])*0.5f;
     }
 }