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Changing definition of Nm and Nk in BlockKrylovSchur

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This commit is contained in:
Chulwoo Jung
2026-04-02 15:22:21 -04:00
parent 88ea24687f
commit 84707cc3a8
4 changed files with 62 additions and 58 deletions
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Grid/algorithms/iterative/HarmonicBlockKrylovSchur.h
+20 -18
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@@ -49,9 +49,9 @@ NAMESPACE_BEGIN(Grid);
*
* A V = V H + F B^dag (1)
*
* with V orthonormal (Nm*Nblock columns), H the (Nm*Nblock)² block
* with V orthonormal (Nm columns), H the Nm² block
* upper-Hessenberg Rayleigh quotient, F the Nblock residual vectors and B
* the (Nm*Nblock)×Nblock coupling matrix, the harmonic Rayleigh quotient
* the Nm×Nblock coupling matrix, the harmonic Rayleigh quotient
* relative to shift σ is
*
* Hhat = H + (H - σI)^{-H} B B^H (2)
@@ -94,8 +94,8 @@ NAMESPACE_BEGIN(Grid);
* ----------
* shift : target shift σ (default 0.0)
* Nblock : block size p
* Nm : number of block steps (total dim = Nm * Nblock)
* Nk : blocks to retain after each restart (Nk < Nm)
* Nm : total Krylov dimension (must be divisible by Nblock)
* Nk : total vectors to retain after each restart (must be divisible by Nblock, Nk < Nm)
* Nstop : stop when this many eigenpairs converge
* MaxIter : maximum outer (restart) iterations
* Tolerance: relative convergence tolerance
@@ -119,8 +119,8 @@ class HarmonicBlockKrylovSchur {
// Parameters
//--------------------------------------------------------------------
int Nblock;
int Nm;
int Nk;
int Nm; // total Krylov dimension (multiple of Nblock)
int Nk; // total vectors retained after restart (multiple of Nblock)
int Nstop;
int MaxIter;
RealD Tolerance;
@@ -173,9 +173,11 @@ public:
Nblock = _Nblock;
assert((int)v0.size() >= Nblock);
assert(Nm % Nblock == 0);
assert(Nk % Nblock == 0);
assert(Nk < Nm);
int N = Nm * Nblock;
int N = Nm;
RealD approxLambdaMax = approxMaxEval(v0[0]);
rtol = Tolerance * approxLambdaMax;
@@ -194,9 +196,9 @@ public:
std::cout << GridLogMessage
<< "HarmonicBlockKrylovSchur: restart iteration " << iter << std::endl;
// ---- Block Arnoldi: extend from block 'start' to block Nm ----
blockArnoldiIteration(startBlock, Nm, start, doubleOrthog);
start = Nk;
// ---- Block Arnoldi: extend from block 'start' to block Nm/Nblock ----
blockArnoldiIteration(startBlock, Nm/Nblock, start, doubleOrthog);
start = Nk/Nblock;
if (doVerify) {
std::string lbl = "iter " + std::to_string(iter) + " after Arnoldi";
@@ -209,12 +211,12 @@ public:
// ---- Schur decompose Hhat ----
ComplexSchurDecomposition schur(Hhat, false, ritzFilter);
schur.schurReorder(Nk * Nblock);
schur.schurReorder(Nk);
std::cout << GridLogMessage
<< "HarmonicBlockKrylovSchur: harmonic Ritz values (first Nk*Nblock):" << std::endl;
<< "HarmonicBlockKrylovSchur: harmonic Ritz values (first Nk):" << std::endl;
CMat S = schur.getMatrixS();
for (int i = 0; i < Nk * Nblock; i++)
for (int i = 0; i < Nk; i++)
std::cout << GridLogMessage << " [" << i << "] " << S(i, i) << std::endl;
CMat Q = schur.getMatrixQ();
@@ -229,8 +231,8 @@ public:
H = Q * H * Qt;
B = Q * B;
// ---- Truncate to Nk*Nblock ----
int Nkeep = Nk * Nblock;
// ---- Truncate to Nk ----
int Nkeep = Nk;
CMat Htmp = H(Eigen::seqN(0, Nkeep), Eigen::seqN(0, Nkeep));
H = CMat::Zero(N, N);
@@ -440,7 +442,7 @@ private:
void blockArnoldiIteration(std::vector<Field>& startBlock, int endBlock,
int startIdx, bool doubleOrthog)
{
int N = Nm * Nblock;
int N = Nm;
if (startIdx == 0) {
basis.clear();
@@ -492,7 +494,7 @@ private:
{
int kBase = k * Nblock;
int prevN = kBase + Nblock;
int N = Nm * Nblock;
int N = Nm;
std::vector<Field> W(Nblock, Field(Grid_));
for (int t = 0; t < Nblock; t++)
@@ -514,7 +516,7 @@ private:
F = W;
if (k == Nm - 1) {
if (k == Nm/Nblock - 1) {
// Last block: record coupling in B as R^H (Hermitian conjugate of QR factor)
// KS relation requires B[kBase+t, s] = conj(R[s,t])
CMat R = blockQR(F);