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38 /* This file is completely threadsafe - keep it that way! */
43 #include "config.h" /* for GMX_MAX_OPENMP_THREADS */
47 #include "gromacs/math/vec.h"
48 #include "gromacs/math/vectypes.h"
49 #include "gromacs/mdlib/gmx_omp_nthreads.h"
50 #include "gromacs/pbcutil/ishift.h"
51 #include "gromacs/pbcutil/mshift.h"
52 #include "gromacs/pbcutil/pbc.h"
53 #include "gromacs/utility/gmxassert.h"
65 static void upd_vir(rvec vir, real dvx, real dvy, real dvz)
72 static void calc_x_times_f(int nxf, const rvec x[], const rvec f[], gmx_bool bScrewPBC, const matrix box, matrix x_times_f)
76 for (int i = 0; i < nxf; i++)
78 for (int d = 0; d < DIM; d++)
80 for (int n = 0; n < DIM; n++)
82 x_times_f[d][n] += x[i][d] * f[i][n];
89 /* We should correct all odd x-shifts, but the range of isx is -2 to 2 */
90 if (isx == 1 || isx == -1)
92 for (int d = 0; d < DIM; d++)
94 for (int n = 0; n < DIM; n++)
96 x_times_f[d][n] += box[d][d] * f[i][n];
104 void calc_vir(int nxf, const rvec x[], const rvec f[], tensor vir, bool bScrewPBC, const matrix box)
108 int nthreads = gmx_omp_nthreads_get_simple_rvec_task(emntDefault, nxf * 9);
110 GMX_ASSERT(nthreads >= 1, "Avoids uninitialized x_times_f (warning)");
114 calc_x_times_f(nxf, x, f, bScrewPBC, box, x_times_f);
118 /* Use a buffer on the stack for storing thread-local results.
119 * We use 2 extra elements (=18 reals) per thread to separate thread
120 * local data by at least a cache line. Element 0 is not used.
122 matrix xf_buf[GMX_OPENMP_MAX_THREADS * 3];
124 #pragma omp parallel for num_threads(nthreads) schedule(static)
125 for (int thread = 0; thread < nthreads; thread++)
127 int start = (nxf * thread) / nthreads;
128 int end = std::min(nxf * (thread + 1) / nthreads, nxf);
130 calc_x_times_f(end - start, x + start, f + start, bScrewPBC, box,
131 thread == 0 ? x_times_f : xf_buf[thread * 3]);
134 for (int thread = 1; thread < nthreads; thread++)
136 m_add(x_times_f, xf_buf[thread * 3], x_times_f);
140 for (int d = 0; d < DIM; d++)
142 upd_vir(vir[d], x_times_f[d][XX], x_times_f[d][YY], x_times_f[d][ZZ]);
148 lo_fcv(int i0, int i1, const real x[], const real f[], tensor vir, const int is[], const real box[], gmx_bool bTriclinic)
150 int i, i3, tx, ty, tz;
152 real dvxx = 0, dvxy = 0, dvxz = 0, dvyx = 0, dvyy = 0, dvyz = 0, dvzx = 0, dvzy = 0, dvzz = 0;
156 for (i = i0; (i < i1); i++)
163 xx = x[i3 + XX] - tx * box[XXXX] - ty * box[YYXX] - tz * box[ZZXX];
164 dvxx += xx * f[i3 + XX];
165 dvxy += xx * f[i3 + YY];
166 dvxz += xx * f[i3 + ZZ];
168 yy = x[i3 + YY] - ty * box[YYYY] - tz * box[ZZYY];
169 dvyx += yy * f[i3 + XX];
170 dvyy += yy * f[i3 + YY];
171 dvyz += yy * f[i3 + ZZ];
173 zz = x[i3 + ZZ] - tz * box[ZZZZ];
174 dvzx += zz * f[i3 + XX];
175 dvzy += zz * f[i3 + YY];
176 dvzz += zz * f[i3 + ZZ];
181 for (i = i0; (i < i1); i++)
188 xx = x[i3 + XX] - tx * box[XXXX];
189 dvxx += xx * f[i3 + XX];
190 dvxy += xx * f[i3 + YY];
191 dvxz += xx * f[i3 + ZZ];
193 yy = x[i3 + YY] - ty * box[YYYY];
194 dvyx += yy * f[i3 + XX];
195 dvyy += yy * f[i3 + YY];
196 dvyz += yy * f[i3 + ZZ];
198 zz = x[i3 + ZZ] - tz * box[ZZZZ];
199 dvzx += zz * f[i3 + XX];
200 dvzy += zz * f[i3 + YY];
201 dvzz += zz * f[i3 + ZZ];
205 upd_vir(vir[XX], dvxx, dvxy, dvxz);
206 upd_vir(vir[YY], dvyx, dvyy, dvyz);
207 upd_vir(vir[ZZ], dvzx, dvzy, dvzz);
210 void f_calc_vir(int i0, int i1, const rvec x[], const rvec f[], tensor vir, const t_graph* g, const matrix box)
214 if (g && (g->nnodes > 0))
216 /* Calculate virial for bonded forces only when they belong to
219 start = std::max(i0, g->at_start);
220 end = std::min(i1, g->at_end);
221 lo_fcv(start, end, x[0], f[0], vir, g->ishift[0], box[0], TRICLINIC(box));
223 /* If not all atoms are bonded, calculate their virial contribution
224 * anyway, without shifting back their coordinates.
225 * Note the nifty pointer arithmetic...
229 calc_vir(start - i0, x + i0, f + i0, vir, FALSE, box);
233 calc_vir(i1 - end, x + end, f + end, vir, FALSE, box);
238 calc_vir(i1 - i0, x + i0, f + i0, vir, FALSE, box);