1 files changed, 78 insertions, 0 deletions
diff --git a/examples/ising_no_field.cpp b/examples/ising_no_field.cpp
new file mode 100644
index 0000000..eebd672
--- /dev/null
+++ b/examples/ising_no_field.cpp
@@ -0,0 +1,78 @@
+
+#include <getopt.h>
+#include <iostream>
+#include <chrono>
+
+#define WOLFF_NO_FIELD
+#include "simple_measurement.hpp"
+
+#include <wolff/models/ising.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;
+
+  int opt;
+
+  // take command line arguments
+  while ((opt = getopt(argc, argv, "N:D:L:T:")) != -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;
+    default:
+      exit(EXIT_FAILURE);
+    }
+  }
+
+  // define the spin-spin coupling
+  std::function <double(const ising_t&, const ising_t&)> Z = [] (const ising_t& s1, const ising_t& s2) -> double {
+    return (double)(s1 * s2);
+  };
+
+  // initialize the lattice
+  graph G(D, L);
+
+  // initialize the system
+  system<ising_t, ising_t> S(G, T, Z);
+
+  // 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 <ising_t(std::mt19937&, const system<ising_t, ising_t>&, v_t)> gen_r = gen_ising;
+
+  // 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;
+}
+