made curve comparison method const

Author: JohnCremona

libsrc/eclib/curve.h

@@ -259,7 +259,7 @@ friend class IsogenyClass;
   // (2) list of ap for good p < NP_SORT
   // (3) a1,a2,a3,4,a6
   vector<bigint> sort_key(const int NP_SORT=25) const;
-  int operator<(const CurveRed& E) {return sort_key()<E.sort_key();}
+  int operator<(const CurveRed& E) const {return sort_key()<E.sort_key();}
 private:
   // functions for setting local root numbers:
   int neron(long p, int kod); // p = 2 or 3

libsrc/egros.cc

@@ -76,6 +76,7 @@ vector<CurveRed> egros_from_j_1728(const vector<bigint>& S)
       if (Ered.has_good_reduction_outside_S(S))
         Elist.push_back(Ered);
     }
+  std::sort(Elist.begin(), Elist.end());
   return Elist;
 }
 
@@ -101,6 +102,7 @@ vector<CurveRed> egros_from_j_0(const vector<bigint>& S)
       if (Ered.has_good_reduction_outside_S(S))
         Elist.push_back(Ered);
     }
+  std::sort(Elist.begin(), Elist.end());
   return Elist;
 }
 
@@ -182,6 +184,7 @@ vector<CurveRed> egros_from_j(const bigrational& j, const vector<bigint>& S)
       if (Ered.has_good_reduction_outside_S(S))
         Elist.push_back(Ered);
     }
+  std::sort(Elist.begin(), Elist.end());
   return Elist;
 }
 

tests/out_no_ntl/tegros.out

@@ -113,13 +113,14 @@ Curves with good reduction outside [ 2 3 5 ] and j = 272223782641/164025 do exis
 [0,0,0,72,0] conductor 2304 sort key [ 2304 0 0 4 0 0 -4 2 0 0 4 0 12 10 0 0 4 0 12 0 0 -6 0 0 -10 -18 0 0 0 72 0 ]
 
 Elliptic curves with conductor a power of 11, from their known j-invariants
-2 curves with j = -122023936/161051: [0,-1,1,-1250,31239] [0,-1,1,-10,-20]
-2 curves with j = -52893159101157376/11: [0,-1,1,-946260,354609639] [0,-1,1,-7820,-263580]
+2 curves with j = -122023936/161051: [0,-1,1,-10,-20] [0,-1,1,-1250,31239]
+2 curves with j = -52893159101157376/11: [0,-1,1,-7820,-263580] [0,-1,1,-946260,354609639]
 2 curves with j = -4096/11: [0,-1,1,0,0] [0,-1,1,-40,-221]
 2 curves with j = -121: [1,1,1,-305,7888] [1,1,0,-2,-7]
-2 curves with j = -32768: [0,-1,1,-7,10] [0,-1,1,-887,-10143]
-2 curves with j = -24729001: [1,1,0,-3632,82757] [1,1,1,-30,-76]
-Sorted list:
+2 curves with j = -32768: [0,-1,1,-887,-10143] [0,-1,1,-7,10]
+2 curves with j = -24729001: [1,1,1,-30,-76] [1,1,0,-3632,82757]
+
+Full sorted list:
 conductor 11	[0,-1,1,-7820,-263580]	j = -52893159101157376/11
 conductor 11	[0,-1,1,-10,-20]	j = -122023936/161051
 conductor 11	[0,-1,1,0,0]	j = -4096/11
@@ -135,13 +136,14 @@ conductor 121	[0,-1,1,-40,-221]	j = -4096/11
 
 Possible conductors <= 100 of curves with j=0:    [ 27 36 72 81 ]
 Actual conductors and curves:
-27	[0,0,1,0,0]
 27	[0,0,1,0,-7]
-36	[0,0,0,0,1]
+27	[0,0,1,0,0]
 36	[0,0,0,0,-27]
-Possible conductors < 100 of curves with j=1728: [ 16 32 36 64 72 100 ]
+36	[0,0,0,0,1]
+
+Possible conductors <= 100 of curves with j=1728: [ 16 32 36 64 72 100 ]
 Actual conductors and curves:
-32	[0,0,0,4,0]
 32	[0,0,0,-1,0]
-64	[0,0,0,1,0]
+32	[0,0,0,4,0]
 64	[0,0,0,-4,0]
+64	[0,0,0,1,0]

tests/out_ntl/tegros.out

@@ -113,13 +113,14 @@ Curves with good reduction outside [ 2 3 5 ] and j = 272223782641/164025 do exis
 [0,0,0,72,0] conductor 2304 sort key [ 2304 0 0 4 0 0 -4 2 0 0 4 0 12 10 0 0 4 0 12 0 0 -6 0 0 -10 -18 0 0 0 72 0 ]
 
 Elliptic curves with conductor a power of 11, from their known j-invariants
-2 curves with j = -122023936/161051: [0,-1,1,-1250,31239] [0,-1,1,-10,-20]
-2 curves with j = -52893159101157376/11: [0,-1,1,-946260,354609639] [0,-1,1,-7820,-263580]
+2 curves with j = -122023936/161051: [0,-1,1,-10,-20] [0,-1,1,-1250,31239]
+2 curves with j = -52893159101157376/11: [0,-1,1,-7820,-263580] [0,-1,1,-946260,354609639]
 2 curves with j = -4096/11: [0,-1,1,0,0] [0,-1,1,-40,-221]
 2 curves with j = -121: [1,1,1,-305,7888] [1,1,0,-2,-7]
-2 curves with j = -32768: [0,-1,1,-7,10] [0,-1,1,-887,-10143]
-2 curves with j = -24729001: [1,1,0,-3632,82757] [1,1,1,-30,-76]
-Sorted list:
+2 curves with j = -32768: [0,-1,1,-887,-10143] [0,-1,1,-7,10]
+2 curves with j = -24729001: [1,1,1,-30,-76] [1,1,0,-3632,82757]
+
+Full sorted list:
 conductor 11	[0,-1,1,-7820,-263580]	j = -52893159101157376/11
 conductor 11	[0,-1,1,-10,-20]	j = -122023936/161051
 conductor 11	[0,-1,1,0,0]	j = -4096/11
@@ -135,13 +136,14 @@ conductor 121	[0,-1,1,-40,-221]	j = -4096/11
 
 Possible conductors <= 100 of curves with j=0:    [ 27 36 72 81 ]
 Actual conductors and curves:
-27	[0,0,1,0,0]
 27	[0,0,1,0,-7]
-36	[0,0,0,0,1]
+27	[0,0,1,0,0]
 36	[0,0,0,0,-27]
-Possible conductors < 100 of curves with j=1728: [ 16 32 36 64 72 100 ]
+36	[0,0,0,0,1]
+
+Possible conductors <= 100 of curves with j=1728: [ 16 32 36 64 72 100 ]
 Actual conductors and curves:
-32	[0,0,0,4,0]
 32	[0,0,0,-1,0]
-64	[0,0,0,1,0]
+32	[0,0,0,4,0]
 64	[0,0,0,-4,0]
+64	[0,0,0,1,0]

tests/tegros.cc

@@ -54,13 +54,11 @@ int main(void)
   cout<<endl;
 
   vector<CurveRed> egr_S23_0 = egros_from_j_0(S23);
-  std::sort(egr_S23_0.begin(), egr_S23_0.end());
   cout << egr_S23_0.size()<< " curves with j=0 and good reduction outside "<<S23<<" (should be 72):\n";
   for (auto E1: egr_S23_0) cout<<(Curve)E1<<" conductor "<<E1.conductor()<<" sort key "<<E1.sort_key()<<endl;
   cout<<endl;
 
   vector<CurveRed> egr_S23_1728 = egros_from_j_1728(S23);
-  std::sort(egr_S23_1728.begin(), egr_S23_1728.end());
   cout << egr_S23_1728.size()<< " curves with j=1728 and good reduction outside "<<S23<<" (should be 32):\n";
   for (auto E1: egr_S23_1728) cout<<(Curve)E1<<" conductor "<<E1.conductor()<<" sort key "<<E1.sort_key()<<endl;
   cout<<endl;
@@ -83,8 +81,9 @@ int main(void)
       cout << endl;
       egr_11.insert(egr_11.end(), EE.cbegin(), EE.cend());
     }
+  cout<<endl;
   std::sort(egr_11.begin(), egr_11.end());
-  cout<<"Sorted list:\n";
+  cout<<"Full sorted list:\n";
   for (auto E1: egr_11)
     cout << "conductor " << E1.conductor() << "\t" << (Curve)E1 << "\tj = " << j_invariant(E1) << endl;
   cout << endl;
@@ -117,7 +116,8 @@ int main(void)
   cout << "Actual conductors and curves:\n";
   for (auto E1: E_j_0)
     cout << E1.conductor() << "\t" << (Curve)E1 << endl;
-  cout << "Possible conductors < 100 of curves with j=1728: " << N_j_1728 << endl;
+  cout << endl;
+  cout << "Possible conductors <= 100 of curves with j=1728: " << N_j_1728 << endl;
   cout << "Actual conductors and curves:\n";
   for (auto E1: E_j_1728)
     cout << E1.conductor() << "\t" << (Curve)E1 << endl;