1 files changed, 82 insertions, 5 deletions

diff --git a/src/wolff_vector.c b/src/wolff_vector.c
index bbfc4da..b1584e6 100644
--- a/src/wolff_vector.c
+++ b/src/wolff_vector.c
@@ -47,11 +47,14 @@ int main(int argc, char *argv[]) {
   double *H = (double *)calloc(MAX_Q, sizeof(double));
   double eps = 0;
   bool silent = false;
+  bool record_autocorrelation = false;
+  count_t ac_skip = 1;
+  count_t W = 10;
 
   int opt;
   q_t H_ind = 0;
 
-  while ((opt = getopt(argc, argv, "N:n:D:L:q:T:H:m:e:s")) != -1) {
+  while ((opt = getopt(argc, argv, "N:n:D:L:q:T:H:m:e:saS:W:")) != -1) {
     switch (opt) {
     case 'N':
       N = (count_t)atof(optarg);
@@ -84,6 +87,15 @@ int main(int argc, char *argv[]) {
     case 's':
       silent = true;
       break;
+    case 'a':
+      record_autocorrelation = true;
+      break;
+    case 'S':
+      ac_skip = (count_t)atof(optarg);
+      break;
+    case 'W':
+      W = (count_t)atof(optarg);
+      break;
     default:
       exit(EXIT_FAILURE);
     }
@@ -120,10 +132,9 @@ int main(int argc, char *argv[]) {
   s->M[0] = 1.0 * (double)h->nv;
   s->E = - ((double)h->ne) * s->J(1.0) - s->H(s->n, s->H_info, s->M);
 
-  printf("%g %g\n", s->E, s->M[0]);
-
   double diff = 1e31;
   count_t n_runs = 0;
+  count_t n_steps = 0;
 
   meas_t *E, *clust, **M;
 
@@ -135,6 +146,13 @@ int main(int argc, char *argv[]) {
   E = calloc(1, sizeof(meas_t));
   clust = calloc(1, sizeof(meas_t));
 
+  autocorr_t *autocorr;
+  if (record_autocorrelation) {
+    autocorr = (autocorr_t *)calloc(1, sizeof(autocorr_t));
+    autocorr->W = 2 * W + 1;
+    autocorr->OO = (double *)calloc(2 * W + 1, sizeof(double));
+  }
+
   if (!silent) printf("\n");
   while (((diff > eps || diff != diff) && n_runs < N) || n_runs < min_runs) {
     if (!silent) printf("\033[F\033[JWOLFF: sweep %" PRIu64
@@ -151,7 +169,16 @@ int main(int argc, char *argv[]) {
       free(step);
       n_flips += tmp_flips;
 
-      update_meas(clust, tmp_flips);
+      if (n_runs > 0) {
+        n_steps++;
+        update_meas(clust, tmp_flips);
+      }
+
+      if (record_autocorrelation && n_runs > 0) {
+        if (n_steps % ac_skip == 0) {
+          update_autocorr(autocorr, s->E);
+        }
+      }
     }
 
     for (q_t i = 0; i < q; i++) {
@@ -170,6 +197,56 @@ int main(int argc, char *argv[]) {
          ", dH/H = %.4f, dM/M = %.4f, dC/C = %.4f, dX/X = %.4f, cps: %.1f\n",
          n_runs, fabs(E->dx / E->x), M[0]->dx / M[0]->x, E->dc / E->c, M[0]->dc / M[0]->c, h->nv / clust->x);
 
+  double tau = 0;
+  bool tau_failed = false;
+
+  if (record_autocorrelation) {
+    double *Gammas = (double *)malloc((W + 1) * sizeof(double));
+
+    Gammas[0] = 1 + rho(autocorr, 0);
+    for (uint64_t i = 0; i < W; i++) {
+      Gammas[1 + i] = rho(autocorr, 2 * i + 1) + rho(autocorr, 2 * i + 2);
+    } 
+
+    uint64_t n;
+    for (n = 0; n < W + 1; n++) {
+      if (Gammas[n] <= 0) {
+        break;
+      }
+    }
+
+    if (n == W + 1) {
+      printf("WARNING: correlation function never hit the noise floor.\n");
+      tau_failed = true;
+    }
+
+    if (n < 2) {
+      printf("WARNING: correlation function only has one nonnegative term.\n");
+      tau_failed = true;
+    }
+
+    double *conv_Gamma = get_convex_minorant(n, Gammas);
+
+    double ttau = - 0.5;
+
+    for (uint64_t i = 0; i < n + 1; i++) {
+      ttau += conv_Gamma[i];
+    }
+    
+    free(Gammas);
+    free(autocorr->OO);
+    while (autocorr->Op != NULL) {
+      stack_pop_d(&(autocorr->Op));
+    }
+    free(autocorr);
+    
+    tau = ttau * ac_skip * clust->x / h->nv;
+  }
+
+  if (tau_failed) {
+    tau = 0;
+  }
+
   FILE *outfile = fopen("out.m", "a");
 
   fprintf(outfile, "<|D->%" PRID ",L->%" PRIL ",q->%" PRIq ",T->%.15f", D, L, q, T);
@@ -201,7 +278,7 @@ int main(int argc, char *argv[]) {
       fprintf(outfile, ",");
     }
   }
-  fprintf(outfile, "}|>\n");
+  fprintf(outfile, "},Subscript[n,\"clust\"]->%.15f,Subscript[\\[Delta]n,\"clust\"]->%.15f,Subscript[m,\"clust\"]->%.15f,Subscript[\\[Delta]m,\"clust\"]->%.15f,\\[tau]->%.15f|>\n", clust->x / h->nv, clust->dx / h->nv, clust->c / h->nv, clust->dc / h->nv,tau);
 
   fclose(outfile);