void FdmGaussSeidelSolver3::relax(const MatrixCsrD& A, const VectorND& b,
double sorFactor, VectorND* x_) {
const auto rp = A.rowPointersBegin();
const auto ci = A.columnIndicesBegin();
const auto nnz = A.nonZeroBegin();
VectorND& x = *x_;
b.forEachIndex([&](size_t i) {
const size_t rowBegin = rp[i];
const size_t rowEnd = rp[i + 1];
double r = 0.0;
double diag = 1.0;
for (size_t jj = rowBegin; jj < rowEnd; ++jj) {
size_t j = ci[jj];
if (i == j) {
diag = nnz[jj];
} else {
r += nnz[jj] * x[j];
}
}
x[i] = (1.0 - sorFactor) * x[i] + sorFactor * (b[i] - r) / diag;
});
}
void SetUp(const ::benchmark::State& state) {
std::mt19937 rng{0};
std::uniform_real_distribution<> d(0.0, 1.0);
const auto n = static_cast<size_t>(state.range(0));
mat.resize(n, n);
x.resize(n);
y.resize(n);
mat.forEachIndex([&](size_t i, size_t j) { mat(i, j) = d(rng); });
x.forEachIndex([&](size_t i) {
x[i] = d(rng);
y[i] = d(rng);
});
}
void FdmIccgSolver2::PreconditionerCompressed::solve(const VectorND& b,
VectorND* x) {
const ssize_t size = static_cast<ssize_t>(b.size());
const auto rp = A->rowPointersBegin();
const auto ci = A->columnIndicesBegin();
const auto nnz = A->nonZeroBegin();
b.forEachIndex([&](size_t i) {
const size_t rowBegin = rp[i];
const size_t rowEnd = rp[i + 1];
double sum = b[i];
for (size_t jj = rowBegin; jj < rowEnd; ++jj) {
size_t j = ci[jj];
if (j < i) {
sum -= nnz[jj] * y[j];
}
}
y[i] = sum * d[i];
});
for (ssize_t i = size - 1; i >= 0; --i) {
const size_t rowBegin = rp[i];
const size_t rowEnd = rp[i + 1];
double sum = y[i];
for (size_t jj = rowBegin; jj < rowEnd; ++jj) {
ssize_t j = static_cast<ssize_t>(ci[jj]);
if (j > i) {
sum -= nnz[jj] * (*x)[j];
}
}
(*x)[i] = sum * d[i];
}
}