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Daniel Richtmann 2017-11-06 18:09:48 +01:00
parent fc7d07ade0
commit 8c579d2d4a
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1 changed files with 80 additions and 0 deletions
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80
lib/algorithms/iterative/GeneralisedMinimalResidual.h
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@ -358,6 +358,86 @@ class GeneralisedMinimalResidual : public OperatorFunction<Field> {
}
RealD outerLoopBody(LinearOperatorBase<Field> &Linop, const Field &src, Field &psi, RealD rsd_sq) {
Field w(src._grid);
Field r(src._grid);
std::vector<Field> v(whatDoWePutHere, src._grid); // in MG code: m + 1
std::vector<std::complex<double>> gamma(whatDoWePutHere, 0.); // in MG code: m + 1
MatrixTimer.Start();
Linop.Op(psi, w); // w = D * psi
MatrixTimer.Stop();
LinalgTimer.Start();
r = src - w;
gamma[0] = norm2(r); // do we need an explicit cast? // in MG code: sqrt around/within the norm
v[0] = (1. / gamma[0]) * r;
LinalgTimer.Stop();
for (int i=0; i<whatDoWePutHere; i++) { // in MG code: p->restart_length
arnoldiStep(Linop, v, w, whatDoWePutHere); // in MG code: j
///////////////////////////////////////////////////////////////////////
// Begin of QR Update /////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////
qrUpdate(whatDoWePutHere); // in MG code: j
///////////////////////////////////////////////////////////////////////
// End of QR Update ///////////////////////////////////////////////////
///////////////////////////////////////////////////////////////////////
if ((whatDoWePutHere) || (cp < rsd_sq)) { // in VPGCR code: (k == nstep-1)
// compute solution
return cp;
}
}
}
void arnoldiStep(LinearOperatorBase<Field> &Linop, std::vector<Field> &v, Field &w, int iter) {
MatrixTimer.Start();
Linop.Op(v[iter], w);
MatrixTimer.Stop();
LinalgTimer.Start();
for(int i = 0; i <= iter; ++i) {
H(i, j) = innerProduct(v[i], w);
w = w - H(i, iter) * v[i];
}
H(iter + 1, iter) = norm2(w); // in MG code: sqrt around/within the norm
v[iter + 1] = (1. / H(iter + 1, iter)) * w;
LinalgTimer.Stop();
}
void qrUpdate(int iter) {
for(int i = 0; i < iter ; ++i) {
auto tmp = -s[i] * H(i, iter) + c[i] * H(i + 1, iter);
H(i, iter) = std::conj(c[i]) * H(i, iter) + std::conj(s[i]) * H(i + 1, iter);
H(i + 1, iter) = tmp;
}
// compute new Givens Rotation
ComplexD nu = sqrt(std::norm(H(iter, iter)) + std::norm(H(iter + 1, iter)));
c[iter] = H(iter, iter) / nu;
s[iter] = H(iter + 1, iter) / nu;
// apply new Givens rotation
H(iter, iter) = nu;
H(iter + 1, iter) = 0.;
/* ORDERING??? */
gamma[iter + 1] = -s[iter] * gamma[iter];
gamma[iter] = std::conj(c[iter]) * gamma[iter];
}
void Step() {