1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
#include <getopt.h>
#include <iostream>
#include <chrono>
#include "simple_measurement.hpp"
#include <wolff/models/potts.hpp>
#include <wolff/models/dihedral.hpp>
#include <wolff/finite_states.hpp>
#include <wolff.hpp>
using namespace wolff;
int main(int argc, char *argv[]) {
// set defaults
N_t N = (N_t)1e4;
D_t D = 2;
L_t L = 128;
double T = 2.26918531421;
vector_t<2, double> H;
H.fill(0.0);
q_t Hi = 0;
int opt;
// take command line arguments
while ((opt = getopt(argc, argv, "N:D:L:T:H:")) != -1) {
switch (opt) {
case 'N': // number of steps
N = (N_t)atof(optarg);
break;
case 'D': // dimension
D = atoi(optarg);
break;
case 'L': // linear size
L = atoi(optarg);
break;
case 'T': // temperature
T = atof(optarg);
break;
case 'H': // external field
H[Hi] = atof(optarg);
Hi++;
break;
default:
exit(EXIT_FAILURE);
}
}
// define the spin-spin coupling
std::function <double(const potts_t<WOLFF_POTTSQ>&, const potts_t<WOLFF_POTTSQ>&)> Z = [] (const potts_t<WOLFF_POTTSQ>& s1, const potts_t<WOLFF_POTTSQ>& s2) -> double {
return cos(2 * M_PI * (double)(s1.x + WOLFF_POTTSQ - s2.x) / (double)WOLFF_POTTSQ);
};
// define the spin-field coupling
std::function <double(const potts_t<WOLFF_POTTSQ>&)> B = [=] (const potts_t<WOLFF_POTTSQ>& s) -> double {
return H[0] * cos(2 * M_PI * (double)s.x / (double)WOLFF_POTTSQ) + H[1] * sin(2 * M_PI * (double)s.x / (double)WOLFF_POTTSQ);
};
// initialize the lattice
graph G(D, L);
// initialize the system
system<dihedral_t<WOLFF_POTTSQ>, potts_t<WOLFF_POTTSQ>> S(G, T, Z, B);
// initialize the random number generator
auto seed = std::chrono::high_resolution_clock::now().time_since_epoch().count();
std::mt19937 rng{seed};
// define function that generates self-inverse rotations
std::function <dihedral_t<WOLFF_POTTSQ>(std::mt19937&, const system<dihedral_t<WOLFF_POTTSQ>, potts_t<WOLFF_POTTSQ>>&, v_t)> gen_r = [] (std::mt19937& r, const system<dihedral_t<WOLFF_POTTSQ>, potts_t<WOLFF_POTTSQ>>& S, v_t i0) -> dihedral_t<WOLFF_POTTSQ> {
dihedral_t<WOLFF_POTTSQ> rot;
rot.is_reflection = true;
std::uniform_int_distribution<q_t> dist(0, WOLFF_POTTSQ - 2);
q_t x = dist(r);
rot.x = (2 * S.s[i0].x + x + 1) % WOLFF_POTTSQ;
return rot;
};
// initailze the measurement object
simple_measurement A(S);
// run wolff N times
S.run_wolff(N, gen_r, A, rng);
// print the result of our measurements
std::cout << "Wolff complete!\nThe average energy per site was " << A.avgE() / S.nv
<< ".\nThe average magnetization per site was " << A.avgM() / S.nv
<< ".\nThe average cluster size per site was " << A.avgC() / S.nv << ".\n";
// exit
return 0;
}
|
