for (i = 0; i < 3; ++i) memcpy(g[i], x + 1, 3 * sizeof(double));
for (i = 0; i < ITER_MAX; ++i)
if (g3_iter(g[1], pdg, 0, n1) < EPS) break;
for (i = 0; i < ITER_MAX; ++i)
if (g3_iter(g[2], pdg, n1, n) < EPS) break;
for (i = 0; i < 3; ++i) memcpy(g[i], x + 1, 3 * sizeof(double));
for (i = 0; i < ITER_MAX; ++i)
if (g3_iter(g[1], pdg, 0, n1) < EPS) break;
for (i = 0; i < ITER_MAX; ++i)
if (g3_iter(g[2], pdg, n1, n) < EPS) break;