Added an input file

heisen.h

@@ -328,26 +328,24 @@ class HeisenCalculation {
 //    astream.close();
 //  }
 
-  HeisenCalculation(int sites) {
-    create_ring(sites);
+  HeisenCalculation(int sites, int sector) {
+    create_ring(sites, sector);
   }
 
-  void create_ring(int sites) {
+  void create_ring(int sites, int sector) {
     double J = 1.0;
     for (int i = 0; i < sites-1; i++) {
       lattice.push_back(Bond(i,i+1,J));
     }
     lattice.push_back(Bond(sites-1,0,J));
-    sectors.push_back(Sector(lattice,sites,1));
-
-//    double J = 1.0;
-//    for (int i = 0; i < sites-1; i++) {
-//      lattice.push_back(Bond(i,i+1,J));
-//    }
-//    lattice.push_back(Bond(sites-1,0,J));
-//    for (int i = 0; i < sites; i++) {
-//      sectors.push_back(Sector(lattice,sites,i));
-//    }
+    if (sector <= 0) {
+      for (int i = 0; i < sites; i++) {
+        sectors.push_back(Sector(lattice,sites,i));
+      }
+    }
+    else {
+      sectors.push_back(Sector(lattice,sites,sector));
+    }
   }
 
   vector<double> eigenvalues() {
@@ -359,8 +357,11 @@ class HeisenCalculation {
       vector<double> mat = s.make_matrix(); 
       vector<double> es(nst,0.0);
       vector<double> ev(nst*nst,0.0);
+      const auto tstart = std::chrono::system_clock::now();
       diag_matrix(mat,nst,es,ev);
-      print_matrix(mat,nst,nst);
+      const auto tstop = std::chrono::system_clock::now();
+      const std::chrono::duration<double> time_elapsed = tstop - tstart;
+      std::cout << "Diagonalization took " << time_elapsed.count() << " s" << std::endl;
       std::copy(es.begin(),es.end(),std::back_inserter(e));
     }
     std::sort(e.begin(),e.end(),[](const double& a, const double& b) {return a < b;});

read.in

@@ -1 +1,2 @@
-4
+14
+6

test_heisen.cc

@@ -1,8 +1,21 @@
 #include "heisen.h"
 
 int main(int argc, char** argv) {
-  HeisenCalculation calc(4);
+  ifstream f("read.in");
+  int nsites = 4;
+  int sector = -1;
+  if (f.is_open()) {
+    f >> nsites; 
+    f >> sector; 
+    printf("read.in --> nsites = %d     sector = %d\n", nsites, sector);
+    f.close();
+  }
+  HeisenCalculation calc(nsites,sector);
+//  const auto tstart = std::chrono::system_clock::now();
   vector<double> e = calc.eigenvalues();
+//  const auto tstop = std::chrono::system_clock::now();
+//  const std::chrono::duration<double> time_elapsed = tstop - tstart;
   print_vector(e);
+//  std::cout << "Calculation took " << time_elapsed.count() << " s" << std::endl;
   return 0;
 }