From 3e9beab27c343d1008199302e644c3e740d66592 Mon Sep 17 00:00:00 2001
From: Jaron Kent-Dobias <jaron@kent-dobias.com>
Date: Mon, 2 Aug 2021 14:16:02 +0200
Subject: Effort started to compare energy autocorrelation time to self-inverse
 scattering.

---
 ciamarra.cpp        |   1 -
 distinguishable.cpp |  11 ++++-
 quantity.hpp        | 119 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+), 2 deletions(-)
 create mode 100644 quantity.hpp

diff --git a/ciamarra.cpp b/ciamarra.cpp
index d1087a4..d3acc38 100644
--- a/ciamarra.cpp
+++ b/ciamarra.cpp
@@ -118,7 +118,6 @@ class CiamarraSystem : public HardSystem<D, CiamarraState<D>> {
   }
 };
 
-
 void print(const CiamarraSystem<2>& s) {
   for (const Vertex<2, CiamarraState<2>>& v : s.vertices) {
     if (v.state(0) == 1 && v.state(1) == 0) {
diff --git a/distinguishable.cpp b/distinguishable.cpp
index b739927..0aae0c1 100644
--- a/distinguishable.cpp
+++ b/distinguishable.cpp
@@ -1,6 +1,7 @@
 #include <iostream>
 
 #include "glass.hpp"
+#include "quantity.hpp"
 
 class DistinguishableState {
 public:
@@ -71,6 +72,7 @@ int main() {
     }
   }
 
+
   unsigned n = 1;
   for (double T = Tmax; T > Tmin; T -= δT) {
 
@@ -86,6 +88,7 @@ int main() {
     std::cout << T << " ";
     s.setInitialPosition();
     auto start = std::chrono::high_resolution_clock::now();
+    Quantity<double> energy(1e3);
     for (unsigned i = 0; i < 1e5; i++) {
       for (unsigned j = 0; j < s.vertices.size(); j++) {
         s.tryRandomSwap(T, r);
@@ -96,9 +99,10 @@ int main() {
       s.wolff(Transformation<D>(L, m, v.position - m * v.position), T, r);
       */
       if (i % 10 == 0) {
+        energy.add(s.energy());
         auto stop = std::chrono::high_resolution_clock::now();
         auto duration = duration_cast<std::chrono::microseconds>(stop - start);
-        std::cout << duration.count() << " " << s.selfIntermediateScattering(ms) << " ";
+        std::cout /*<< duration.count() << " "*/ << s.selfIntermediateScattering(ms) << " ";
       }
     }
     /*
@@ -110,6 +114,11 @@ int main() {
     }
     */
     std::cout << std::endl;
+    std::vector<double> rho = energy.ρ();
+    for (const double& x : rho) {
+      std::cout << x << " ";
+    }
+    std::cout << std::endl;
     std::cerr << T << " " << s.energy() / N << std::endl;
     //    s.sweepLocal(r);
     //    s.sweepSwap(r);
diff --git a/quantity.hpp b/quantity.hpp
new file mode 100644
index 0000000..400a0dd
--- /dev/null
+++ b/quantity.hpp
@@ -0,0 +1,119 @@
+
+#pragma once
+
+#include <array>
+#include <cmath>
+#include <list>
+#include <vector>
+#include <fstream>
+#include <iomanip>
+
+template <class T>
+class Quantity {
+private:
+  uint64_t N;
+  uint64_t n;
+  unsigned skip;
+  std::list<T> hist;
+  double total;
+  double total2;
+  std::vector<double> C;
+
+public:
+  Quantity(unsigned lag, unsigned s = 1) : C(lag) {
+    skip = s;
+    N = 0;
+    n = 0;
+    total = 0;
+    total2 = 0;
+  }
+
+  void read(std::string filename) {
+    std::ifstream inFile(filename);
+    inFile >> n;
+    inFile >> total;
+    inFile >> total2;
+
+    for (double& Ci : C) {
+      inFile >> Ci;
+    }
+  }
+
+  void write(std::string filename) const {
+    std::ofstream outFile(filename);
+    outFile << std::setprecision(15) << n << " " << total << " " << total2 << std::endl;
+    for (double Ci : C) {
+      outFile << Ci << " ";
+    }
+    outFile << std::endl;
+    outFile.close();
+  }
+
+  void reset() {
+    total = 0;
+    total2 = 0;
+    std::fill(C.begin(), C.end(), 0);
+    n = 0;
+    hist = {};
+  }
+
+  void add(const T& x) {
+    if (N % skip == 0) {
+      hist.push_front(x);
+      if (hist.size() > C.size()) {
+        hist.pop_back();
+        unsigned t = 0;
+        for (T a : hist) {
+          C[t] += a * x;
+          t++;
+        }
+        double norm = x * x;
+        total += sqrt(norm);
+        total2 += norm;
+        n++;
+      }
+    }
+    N++;
+  }
+
+  double avg() const { return total / n; }
+
+  double avg2() const { return total2 / n; }
+
+  std::vector<double> ρ() const {
+    double C0 = C.front() / n;
+    double avg2 = pow(total / n, 2);
+
+    std::vector<double> ρtmp;
+
+    for (double Ct : C) {
+      ρtmp.push_back((Ct / n - avg2) / (C0 - avg2));
+    }
+
+    return ρtmp;
+  }
+
+  std::array<double, 2> τ() const {
+    double τtmp = 0.5;
+    unsigned M = 1;
+    double c = 8.0;
+
+    std::vector<double> ρ_tmp = this->ρ();
+
+    while (c * τtmp > M && M < C.size()) {
+      τtmp += ρ_tmp[M];
+      M++;
+    }
+
+    return {skip * τtmp, skip * 2.0 * (2.0 * M + 1) * pow(τtmp, 2) / n};
+  }
+
+  double σ() const {
+    return 2.0 / n * this->τ()[0] * (C[0] / n - pow(this->avg(), 2));
+  }
+
+  double serr() const { return sqrt(this->σ()); }
+
+  unsigned num_added() const { return n; }
+};
+
-- 
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