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#include <vector> | |
#include <tuple> | |
#include <amgcl/make_solver.hpp> | |
#include <amgcl/preconditioner/runtime.hpp> | |
#include <amgcl/solver/runtime.hpp> | |
#include <amgcl/adapter/crs_tuple.hpp> | |
#include <amgcl/adapter/zero_copy.hpp> | |
#include <amgcl/profiler.hpp> | |
// Generates matrix for poisson problem in a unit cube. | |
template <typename PointerType, typename ColumnType, typename ValueType, typename RhsType> | |
int sample_problem( | |
ptrdiff_t n, | |
std::vector<PointerType> &ptr, | |
std::vector<ColumnType> &col, | |
std::vector<ValueType> &val, | |
std::vector<RhsType> &rhs, | |
double anisotropy = 1.0 | |
) | |
{ | |
ptrdiff_t n3 = n * n * n; | |
ptr.clear(); | |
col.clear(); | |
val.clear(); | |
rhs.clear(); | |
ptr.reserve(n3 + 1); | |
col.reserve(n3 * 7); | |
val.reserve(n3 * 7); | |
rhs.reserve(n3); | |
ValueType one = amgcl::math::identity<ValueType>(); | |
double hx = 1; | |
double hy = hx * anisotropy; | |
double hz = hy * anisotropy; | |
ptr.push_back(0); | |
for(ptrdiff_t k = 0, idx = 0; k < n; ++k) { | |
for(ptrdiff_t j = 0; j < n; ++j) { | |
for (ptrdiff_t i = 0; i < n; ++i, ++idx) { | |
if (k > 0) { | |
col.push_back(idx - n * n); | |
val.push_back(-1.0/(hz * hz) * one); | |
} | |
if (j > 0) { | |
col.push_back(idx - n); | |
val.push_back(-1.0/(hy * hy) * one); | |
} | |
if (i > 0) { | |
col.push_back(idx - 1); | |
val.push_back(-1.0/(hx * hx) * one); | |
} | |
col.push_back(idx); | |
val.push_back((2 / (hx * hx) + 2 / (hy * hy) + 2 / (hz * hz)) * one); | |
if (i + 1 < n) { | |
col.push_back(idx + 1); | |
val.push_back(-1.0/(hx * hx) * one); | |
} | |
if (j + 1 < n) { | |
col.push_back(idx + n); | |
val.push_back(-1.0/(hy * hy) * one); | |
} | |
if (k + 1 < n) { | |
col.push_back(idx + n * n); | |
val.push_back(-1.0/(hz * hz) * one); | |
} | |
rhs.push_back( amgcl::math::constant<RhsType>(1.0) ); | |
ptr.push_back( static_cast<PointerType>(col.size()) ); | |
} | |
} | |
} | |
return n3; | |
} | |
//--------------------------------------------------------------------------- | |
template <typename PointerType, typename ColumnType, typename ValueType, typename RhsType> | |
void solve( | |
// Matrix in CRS format: | |
const std::vector<PointerType> &ptr, | |
const std::vector<ColumnType> &col, | |
const std::vector<ValueType> &val, | |
// RHS: | |
const std::vector<RhsType> &rhs, | |
// Initial solution on input, solution on output: | |
std::vector<RhsType> &x | |
) | |
{ | |
typedef amgcl::backend::builtin<ValueType, ColumnType, PointerType> Backend; | |
typedef amgcl::make_solver< | |
amgcl::runtime::preconditioner<Backend>, | |
amgcl::runtime::solver::wrapper<Backend> | |
> Solver; | |
boost::property_tree::ptree prm; | |
prm.put("solver.tol", 1e-6); | |
PointerType n = ptr.size() - 1; | |
amgcl::profiler<> prof; | |
// setup the solver: | |
prof.tic("setup"); | |
auto A = amgcl::adapter::zero_copy_direct(n, ptr.data(), col.data(), val.data()); | |
amgcl::backend::sort_rows(*A); | |
Solver solve(A, prm); | |
prof.toc("setup"); | |
std::cout << solve << std::endl; | |
// solve the problem: | |
int iters; | |
double error; | |
prof.tic("solve"); | |
std::tie(iters, error) = solve(rhs, x); | |
prof.toc("solve"); | |
std::cout << "Iterations: " << iters << std::endl; | |
std::cout << "Error : " << error << std::endl; | |
std::cout << prof << std::endl; | |
} | |
//--------------------------------------------------------------------------- | |
int main(int argc, char *argv[]) { | |
int n = argc > 1 ? std::stoi(argv[1]) : 32; | |
std::vector<ptrdiff_t> ptr; | |
std::vector<int> col; | |
std::vector<double> val, rhs; | |
int n3 = sample_problem(n, ptr, col, val, rhs); | |
std::vector<double> x(n3, 0.0); | |
solve(ptr, col, val, rhs, x); | |
} |
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amgcl: amgcl.cpp | |
g++ -O3 -fopenmp -DNDEBUG -I$(HOME)/work/amgcl -o amgcl amgcl.cpp |
Author
ddemidov
commented
Nov 14, 2018
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