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complex davidson - compilable but not tested yet

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Jiri Pittner
2022-06-08 21:22:01 +02:00
parent 3ea56da8d5
commit 12585b0bd3
3 changed files with 34 additions and 8 deletions
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19
davidson.h
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@@ -27,7 +27,7 @@
namespace LA {
//Davidson diagonalization of real symmetric matrix (modified Lanczos), works also for right eigenvectors on non-symmetric matrix
//should work for complex hermitian-only too, but was not tested yet (maybe somwhere complex conjugation will have to be added)
//matrix can be any class which has nrows(), ncols(), diagonalof(), issymmetric(), and gemv() available
//does not even have to be explicitly stored - direct CI
//therefore the whole implementation must be a template in a header
@@ -57,7 +57,7 @@ if(eivals.size()<nroots) laerror("too small eivals dimension in davidson");
NRVec<T> vec1(n),vec2(n);
NRMat<T> smallH(maxkrylov,maxkrylov),smallS(maxkrylov,maxkrylov),smallV;
NRVec<T> r(maxkrylov);
NRVec<typename LA_traits<T>::normtype> r(maxkrylov);
NRVec<T> *v0,*v1;
AuxStorage<T> *s0,*s1;
@@ -87,9 +87,9 @@ if(initguess) initguess(vec1);
else
{
const T *diagonal = bigmat.diagonalof(vec2,false,true);
T t=1e100; int i,j;
typename LA_traits<T>::normtype t=1e100; int i,j;
vec1=0;
for(i=0, j= -1; i<n; ++i) if(diagonal[i]<t) {t=diagonal[i]; j=i;}
for(i=0, j= -1; i<n; ++i) if(LA_traits<T>::realpart(diagonal[i])<t) {t=LA_traits<T>::realpart(diagonal[i]); j=i;}
vec1[j]=1;
}
@@ -145,14 +145,17 @@ if(bigmat.issymmetric())
}
else
{
NRVec<T> ri(krylovsize+1),beta(krylovsize+1);
NRVec<typename LA_traits<T>::normtype> ri(krylovsize+1);
NRVec<T> beta(krylovsize+1);
NRMat<T> scratch;
scratch=smallV;
gdiagonalize(scratch, r, ri,NULL, &smallV, 1, krylovsize+1, 2, 0, &smallSwork, &beta);
for(int i=0; i<=krylovsize; ++i) {r[i]/=beta[i]; ri[i]/=beta[i];}
//the following is definitely NOT OK for non-hermitian complex matrices, but we do not support these
//it is just to make the code compilable for T both real and complex
for(int i=0; i<=krylovsize; ++i) {r[i]/=LA_traits<T>::realpart(beta[i]); ri[i]/=LA_traits<T>::realpart(beta[i]);}
}
T eival_n=r[nroot];
typename LA_traits<T>::normtype eival_n=r[nroot];
oldnroot=nroot;
typename LA_traits<T>::normtype test=std::abs(smallV(krylovsize,nroot));
if(test<eps) nroot++;
@@ -204,7 +207,7 @@ const T *diagonal = bigmat.diagonalof(vec2,false,true);
eival_n = r[nroot];
for(i=0; i<n; ++i)
{
T denom = diagonal[i] - eival_n;
typename LA_traits<T>::normtype denom = LA_traits<T>::realpart(diagonal[i]) - eival_n;
denom = denom<0?-std::max(0.1,std::abs(denom)):std::max(0.1,std::abs(denom));
vec1[i] /= denom;
}