From 98916c597dcaafd8113547a39d1e66704ac62b82 Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Fri, 19 Oct 2018 11:05:32 -0400
Subject: added support for nonunitary x, so that bond probabilities can be
 changed as in the DGM paper

---
 lib/include/wolff.hpp         | 4 ++--
 lib/include/wolff/cluster.hpp | 8 ++++----
 lib/include/wolff/system.hpp  | 4 ++--
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/lib/include/wolff.hpp b/lib/include/wolff.hpp
index 7e909c8..7ad608f 100644
--- a/lib/include/wolff.hpp
+++ b/lib/include/wolff.hpp
@@ -10,7 +10,7 @@ namespace wolff{
 template <class R_t, class X_t>
 void system<R_t, X_t>::run_wolff(N_t N,
            std::function <R_t(std::mt19937&, const system<R_t, X_t>&, v_t)> r_gen,
-           measurement<R_t, X_t>& A, std::mt19937& rng) {
+           measurement<R_t, X_t>& A, std::mt19937& rng, double x) {
 
   std::uniform_int_distribution<v_t> dist(0, nv - 1);
 
@@ -20,7 +20,7 @@ void system<R_t, X_t>::run_wolff(N_t N,
 
     A.pre_cluster(n, N, *this, i0, r);
 
-    this->flip_cluster(i0, r, rng, A);
+    this->flip_cluster(i0, r, rng, A, x);
 
     A.post_cluster(n, N, *this);
   }
diff --git a/lib/include/wolff/cluster.hpp b/lib/include/wolff/cluster.hpp
index b66f367..34d256a 100644
--- a/lib/include/wolff/cluster.hpp
+++ b/lib/include/wolff/cluster.hpp
@@ -13,7 +13,7 @@ namespace wolff {
 
 template <class R_t, class X_t>
 void system<R_t, X_t>::flip_cluster(v_t i0, const R_t& r,
-                  std::mt19937& rng, measurement<R_t, X_t>& A) {
+                  std::mt19937& rng, measurement<R_t, X_t>& A, double x) {
   std::uniform_real_distribution<double> dist(0.0, 1.0);
 
   std::queue<v_t> queue;
@@ -69,7 +69,7 @@ void system<R_t, X_t>::flip_cluster(v_t i0, const R_t& r,
 #endif
 
 #ifdef WOLFF_FINITE_STATES
-          p = finite_states_Bp[finite_states_enum(s0s_old)]
+          p = 1.0 - x + x * finite_states_Bp[finite_states_enum(s0s_old)]
                               [finite_states_enum(s0s_new)];
 #endif
 
@@ -85,7 +85,7 @@ void system<R_t, X_t>::flip_cluster(v_t i0, const R_t& r,
 #endif
 
 #ifdef WOLFF_FINITE_STATES
-          p = finite_states_Zp[finite_states_enum(s[i])]
+          p = 1.0 - x + x * finite_states_Zp[finite_states_enum(s[i])]
                               [finite_states_enum(si_new)]
                               [finite_states_enum(s[j])];
 #endif
@@ -95,7 +95,7 @@ void system<R_t, X_t>::flip_cluster(v_t i0, const R_t& r,
         }
 
 #ifndef FINITE_STATES
-        p = 1.0 - exp(-dE / T);
+        p = 1.0 - x * exp(-dE / T);
 #endif
 
         if (dist(rng) < p) {
diff --git a/lib/include/wolff/system.hpp b/lib/include/wolff/system.hpp
index 32ad38e..6e9c951 100644
--- a/lib/include/wolff/system.hpp
+++ b/lib/include/wolff/system.hpp
@@ -68,8 +68,8 @@ class system {
 #endif
     }
 
-    void flip_cluster(v_t, const R_t&, std::mt19937&, measurement<R_t, X_t>&);
-    void run_wolff(N_t, std::function <R_t(std::mt19937&, const system<R_t, X_t>&, v_t)> r_gen, measurement<R_t, X_t>& A, std::mt19937& rng);
+    void flip_cluster(v_t, const R_t&, std::mt19937&, measurement<R_t, X_t>&, double x = 1.0);
+    void run_wolff(N_t, std::function <R_t(std::mt19937&, const system<R_t, X_t>&, v_t)> r_gen, measurement<R_t, X_t>& A, std::mt19937& rng, double x = 1.0);
 };
 
 }
-- 
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