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Starting Harmonic (shift and inverse)

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This commit is contained in:
Chulwoo Jung
2025-11-24 17:05:35 -05:00
parent 0b457b9d52
commit 3538faf449
2 changed files with 22 additions and 8 deletions
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Grid/algorithms/iterative/KrylovSchur.h
+17 -3
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@@ -290,10 +290,11 @@ class KrylovSchur {
RitzFilter ritzFilter; // how to sort evals
public:
RealD *shift; // for Harmonic (shift and invert)
KrylovSchur(LinearOperatorBase<Field> &_Linop, GridBase *_Grid, RealD _Tolerance, RitzFilter filter = EvalReSmall)
: Linop(_Linop), Grid(_Grid), Tolerance(_Tolerance), ritzFilter(filter), u(_Grid), MaxIter(-1), Nm(-1), Nk(-1), Nstop (-1),
evals (0), ritzEstimates (), evecs (), ssq (0.0), rtol (0.0), beta_k (0.0), approxLambdaMax (0.0)
evals (0), ritzEstimates (), evecs (), ssq (0.0), rtol (0.0), beta_k (0.0), approxLambdaMax (0.0),shift(NULL)
{
u = Zero();
};
@@ -316,6 +317,10 @@ class KrylovSchur {
* - Truncate the Krylov-Schur expansion.
*/
void operator()(const Field& v0, int _maxIter, int _Nm, int _Nk, int _Nstop, bool doubleOrthog = true) {
RealD shift_=1.;
shift = &shift_;
if (shift)
std::cout << GridLogMessage << "Shift " << approxLambdaMax << std::endl;
MaxIter = _maxIter;
Nm = _Nm; Nk = _Nk;
Nstop = _Nstop;
@@ -347,7 +352,16 @@ class KrylovSchur {
// Perform a Schur decomposition on Rayleigh
// ComplexSchurDecomposition schur (Rayleigh, false);
Eigen::MatrixXcd temp = Rayleigh;
for (int m=0;m<Nm;m++) temp(m,m) -= *shift;
Eigen::MatrixXcd RayleighS = temp.inverse();
Eigen::MatrixXcd temp2 = RayleighS*temp;
std::cout << GridLogMessage << "Shift inverse check: shift= "<<*shift <<std::endl;
ComplexSchurDecomposition schur (Rayleigh, false, ritzFilter);
ComplexSchurDecomposition schurS (RayleighS, false, ritzFilter);
std::cout << GridLogDebug << "Schur decomp holds? " << schur.checkDecomposition() << std::endl;
// Rearrange Schur matrix so wanted evals are on top left (like MATLAB's ordschur)
@@ -457,8 +471,8 @@ class KrylovSchur {
basis.push_back(v0Norm * v0); // normalized source
// basis[0] = v0Norm * v0; // normalized source
Rayleigh = Eigen::MatrixXcd::Zero(Nm, Nm);
u = Zero();
Rayleigh = Eigen::MatrixXcd::Zero(Nm, Nm); // CJ: B in SLEPc
u = Zero();
} else {
// assert( start == basis.size() ); // should be starting at the end of basis (start = Nk)
std::cout << GridLogMessage << "Resetting Rayleigh and b" << std::endl;