Sorting eval/evec according to RitzFilter

Grid/algorithms/iterative/BlockKrylovSchur.h

@@ -30,6 +30,7 @@ See the full license in the file "LICENSE" in the top level distribution directo
 #define GRID_BLOCKED_KRYLOV_SCHUR_H
 
 #include <iomanip>
+#include <numeric>
 
 NAMESPACE_BEGIN(Grid);
 
@@ -697,8 +698,22 @@ private:
   {
     Eigen::ComplexEigenSolver<CMat> es;
     es.compute(Hk);
-    evals      = es.eigenvalues();
+
-    littleEvecs = es.eigenvectors();
+    // Sort to match schurReorder ordering.
+    int n = es.eigenvalues().size();
+    ComplexComparator cComp(ritzFilter);
+    std::vector<int> idx(n);
+    std::iota(idx.begin(), idx.end(), 0);
+    std::sort(idx.begin(), idx.end(), [&](int a, int b){
+      return cComp(toStdCmplx(es.eigenvalues()(a)), toStdCmplx(es.eigenvalues()(b)));
+    });
+
+    evals.resize(n);
+    littleEvecs.resize(n, n);
+    for (int k = 0; k < n; k++) {
+      evals(k)           = es.eigenvalues()(idx[k]);
+      littleEvecs.col(k) = es.eigenvectors().col(idx[k]);
+    }
 
     evecs.clear();
     for (int k = 0; k < Nkeep; k++) {
@@ -735,6 +750,7 @@ private:
       std::cout << GridLogMessage << "BlockKrylovSchur: Ritz estimate[" << k
                 << "] = " << res << "  eval = " << evals[k] << std::endl;
       if (res < rtol) Nconv++;
+      else break;
     }
     return Nconv;
   }

Grid/algorithms/iterative/HarmonicBlockKrylovSchur.h

@@ -30,6 +30,7 @@ See the full license in the file "LICENSE" in the top level distribution directo
 #define GRID_HARMONIC_BLOCKED_KRYLOV_SCHUR_H
 
 #include <iomanip>
+#include <numeric>
 
 NAMESPACE_BEGIN(Grid);
 
@@ -574,8 +575,22 @@ private:
   {
     Eigen::ComplexEigenSolver<CMat> es;
     es.compute(Hk);
-    evals       = es.eigenvalues();
+
-    littleEvecs = es.eigenvectors();
+    // Sort to match schurReorder ordering.
+    int n = es.eigenvalues().size();
+    ComplexComparator cComp(ritzFilter);
+    std::vector<int> idx(n);
+    std::iota(idx.begin(), idx.end(), 0);
+    std::sort(idx.begin(), idx.end(), [&](int a, int b){
+      return cComp(toStdCmplx(es.eigenvalues()(a)), toStdCmplx(es.eigenvalues()(b)));
+    });
+
+    evals.resize(n);
+    littleEvecs.resize(n, n);
+    for (int k = 0; k < n; k++) {
+      evals(k)           = es.eigenvalues()(idx[k]);
+      littleEvecs.col(k) = es.eigenvectors().col(idx[k]);
+    }
 
     evecs.clear();
     for (int k = 0; k < Nkeep; k++) {
@@ -612,6 +627,7 @@ private:
                 << "HarmonicBlockKrylovSchur: Ritz estimate[" << k
                 << "] = " << res << "  eval = " << evals[k] << std::endl;
       if (res < rtol) Nconv++;
+      else break;
     }
     return Nconv;
   }

Grid/algorithms/iterative/KrylovSchur.h

@@ -105,8 +105,8 @@ struct ComplexComparator
   bool operator()(std::complex<double> z1, std::complex<double> z2) { 
 	  RealD tmp1=std::abs(std::imag(z1));
 	  RealD tmp2=std::abs(std::imag(z2));
-	  if ( std::abs(std::real(z1)) >4.) tmp1 += 100.;
+	  if ( std::abs(std::real(z1)) >2.) tmp1 += 100.;
-	  if ( std::abs(std::real(z2)) >4.) tmp2 += 100.;
+	  if ( std::abs(std::real(z2)) >2.) tmp2 += 100.;
     switch (RF) {
       case EvalNormSmall:
         return std::abs(z1) < std::abs(z2);
@@ -738,35 +738,36 @@ if (!shift){
     {
       std::cout << GridLogMessage << "Computing eigenvalues." << std::endl;
 
-      // evals = S.diagonal();
-      int n = evals.size();       // should be regular Nm
-
       evecs.clear();
-      // evecs.assign(n, Field(Grid));
-
-      // TODO: is there a faster way to get the eigenvectors of a triangular matrix?
-      // Rayleigh.triangularView<Eigen::Upper> tri;
 
       Eigen::ComplexEigenSolver<Eigen::MatrixXcd> es;
-      // es.compute(Rayleigh);
       es.compute(S);
-      evals = es.eigenvalues();
-      littleEvecs = es.eigenvectors();
 
-      // std::cout << GridLogDebug << "Little evecs: " << littleEvecs << std::endl;
+      // Sort eigenvalues/evecs to match the schurReorder ordering.
-      // std::cout << "Rayleigh diag: " << S.diagonal() << std::endl;
+      int n = es.eigenvalues().size();
-      // std::cout << "Rayleigh evals: " << evals << std::endl;
+      ComplexComparator cComp(ritzFilter);
+      std::vector<int> idx(n);
+      std::iota(idx.begin(), idx.end(), 0);
+      std::sort(idx.begin(), idx.end(), [&](int a, int b){
+        return cComp(toStdCmplx(es.eigenvalues()(a)), toStdCmplx(es.eigenvalues()(b)));
+      });
+
+      evals.resize(n);
+      littleEvecs.resize(n, n);
+      for (int k = 0; k < n; k++) {
+        evals(k)          = es.eigenvalues()(idx[k]);
+        littleEvecs.col(k) = es.eigenvectors().col(idx[k]);
+      }
 
       // Convert evecs to lattice fields
       for (int k = 0; k < n; k++) {
         Eigen::VectorXcd vec = littleEvecs.col(k);
         Field tmp (basis[0].Grid());
         tmp = Zero();
-        for (int j = 0; j < basis.size(); j++) {
+        for (int j = 0; j < (int)basis.size(); j++) {
           tmp = tmp + vec[j] * basis[j];
         }
         evecs.push_back(tmp);
-        // evecs[k] = tmp;
       }
     }
 
@@ -831,12 +832,12 @@ if (!shift){
         Eigen::VectorXcd evec_k = littleEvecs.col(k);
         RealD ritzEstimate = std::abs(b.dot(evec_k));           // b^\dagger s
         ritzEstimates.push_back(ritzEstimate);
-        // ritzEstimates[k] = ritzEstimate;
         std::cout << GridLogMessage << "Ritz estimate for evec " << k << " = " << ritzEstimate << std::endl;
         if (ritzEstimate < rtol) {
           Nconv++;
+        } else {
+          break;
         }
-
       }
       // Check that Ritz estimate is explicitly || D (Uy) - lambda (Uy) ||
 //       checkRitzEstimate();

examples/Example_krylov_schur.cc

@@ -338,6 +338,7 @@ int main (int argc, char ** argv)
 #if 0
     KrylovSchur KrySchur (Dwilson, UGrid, resid,EvalImNormSmall);
 //    KrySchur(src[0], maxIter, Nm, Nk, Nstop);
+    KrySchur.doEvalCheck=true;
     KrySchur(src[0], maxIter, Nm, Nk, Nstop,&shift);
     std::cout << GridLogMessage << "KrylovSchur evec.size= " << KrySchur.evecs.size()<< std::endl;
 #else
@@ -345,8 +346,9 @@ int main (int argc, char ** argv)
     Nblock=LanParams.Nblock;
     bool if_verify=false;
     if(LanParams.verify) if_verify=true;
-//    BlockKrylovSchur KrySchur (Dwilson, UGrid, resid,EvalImNormSmall);
+    BlockKrylovSchur KrySchur (Dwilson, UGrid, resid,EvalImNormSmall);
-    HarmonicBlockKrylovSchur KrySchur (Dwilson, UGrid, resid,shift,EvalNormSmall);
+//    HarmonicBlockKrylovSchur KrySchur (Dwilson, UGrid, resid,shift,EvalNormSmall);
+    KrySchur.doEvalCheck=true;
     KrySchur(src, maxIter, Nm, Nk, Nstop,Nblock,true,if_verify);
     std::cout << GridLogMessage << "BlockKrylovSchur evec.size= " << KrySchur.evecs.size()<< std::endl;
 #endif

examples/LanParams.xml

@@ -10,8 +10,10 @@
     <Np>100</Np>
     <ReadEvec>0</ReadEvec>
     <maxIter>1000</maxIter>
+    <reorthog>1</reorthog>
     <Nblock>4</Nblock>
     <verify>0</verify>
+    <shift>1.5</shift>
     <resid>1e-10</resid>
     <ChebyLow>1</ChebyLow>
     <ChebyHigh>100</ChebyHigh>