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jiri 2020-05-20 16:27:52 +00:00
parent 23d53f9a34
commit 3b92abcdb2
1 changed files with 7 additions and 2 deletions
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davidson.h
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@ -26,7 +26,7 @@
namespace LA { namespace LA {
//Davidson diagonalization of real symmetric matrix (modified Lanczos) //Davidson diagonalization of real symmetric matrix (modified Lanczos), works also for right eigenvectors on non-symmetric matrix
//matrix can be any class which has nrows(), ncols(), diagonalof(), issymmetric(), and gemv() available //matrix can be any class which has nrows(), ncols(), diagonalof(), issymmetric(), and gemv() available
//does not even have to be explicitly stored - direct CI //does not even have to be explicitly stored - direct CI
@ -211,7 +211,11 @@ for(i=0; i<n; ++i)
} }
//orthogonalise to previous vectors //orthogonalise to previous vectors
vec1.normalize(); typename LA_traits<T>::normtype vnorm= vec1.norm();
if(vnorm) laerror("Zero Krylov vector in Davidson - perhaps try different initial guess");
else
{
vec1 *= (1./vnorm);
for(j=0; j<=krylovsize; ++j) for(j=0; j<=krylovsize; ++j)
{ {
typename LA_traits<T>::normtype vnorm; typename LA_traits<T>::normtype vnorm;
@ -223,6 +227,7 @@ for(j=0; j<=krylovsize; ++j)
vec1 *= (1./vnorm); vec1 *= (1./vnorm);
} while (vnorm<0.99); } while (vnorm<0.99);
} }
}
//here it is possible to apply some purification procedure if the eivector has to fulfill other conditions //here it is possible to apply some purification procedure if the eivector has to fulfill other conditions
//vec1.normalize(); //after the purification //vec1.normalize(); //after the purification