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133 lines
3.5 KiB
C++
133 lines
3.5 KiB
C++
#include "diffusion.hpp"
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#include <Eigen/SparseCholesky>
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#include <Eigen/SparseLU>
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#include <Eigen/SparseQR>
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#include <Eigen/src/Core/Matrix.h>
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#include <Eigen/src/Core/util/Constants.h>
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#include <Eigen/src/OrderingMethods/Ordering.h>
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#include <Eigen/src/SparseCholesky/SimplicialCholesky.h>
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#include <Eigen/src/SparseCore/SparseMap.h>
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#include <Eigen/src/SparseCore/SparseMatrix.h>
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#include <Eigen/src/SparseCore/SparseMatrixBase.h>
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#include <Eigen/src/SparseLU/SparseLU.h>
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#include <Eigen/src/SparseQR/SparseQR.h>
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#include <iostream>
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#include <iomanip>
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#include <ostream>
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void BTCS1D(int x, std::vector<double> &c, std::vector<double> &alpha,
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double timestep, std::vector<double> &bc) {
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double dx = 1. / x;
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int size = x + 2;
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Eigen::VectorXd b = Eigen::VectorXd::Constant(size, 0);
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Eigen::VectorXd x_out(size);
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std::vector<T> tripletList;
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tripletList.reserve(c.size() * 3 + bc.size());
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int A_line = 0;
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for (int i = 1; i < x + 1; i++) {
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double sx = (alpha[i-1] * timestep) / (dx * dx);
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tripletList.push_back(T(A_line, i, (-1. - 2. * sx)));
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tripletList.push_back(T(A_line, i - 1, sx));
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tripletList.push_back(T(A_line, i + 1, sx));
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b[A_line] = -c[i-1];
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A_line++;
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}
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tripletList.push_back(T(A_line, 0, 1));
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b[A_line] = bc[0];
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A_line++;
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tripletList.push_back(T(A_line, size-1, 1));
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// b[A_line] = bc[1];
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b[A_line] = c[c.size()-1];
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// std::cout << b << std::endl;
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Eigen::SparseMatrix<double> A(size, size);
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A.setFromTriplets(tripletList.begin(), tripletList.end());
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// std::cout << A << std::endl;
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Eigen::SparseQR<Eigen::SparseMatrix<double>, Eigen::COLAMDOrdering<int>>
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solver;
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// Eigen::SparseLU<Eigen::SparseMatrix<double>, Eigen::COLAMDOrdering<int>>
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// solver;
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solver.analyzePattern(A);
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solver.factorize(A);
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std::cout << solver.lastErrorMessage() << std::endl;
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x_out = solver.solve(b);
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std::cout << std::setprecision(10) << x_out << std::endl << std::endl;
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for (int i=0; i < c.size(); i++) {
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c[i] = x_out[i+1];
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}
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}
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void BTCS2D(int x, int y, std::vector<double> &c, std::vector<double> &alpha,
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double timestep) {
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double dx = 1. / x;
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double dy = 1. / y;
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int size = (x - 2) * (y - 2);
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Eigen::VectorXd b = Eigen::VectorXd::Constant(size, 0);
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Eigen::VectorXd x_out(x * y);
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std::vector<T> tripletList;
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tripletList.reserve(size * 5);
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int A_line = 0;
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for (int i = 1; i < y - 1; i++) {
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for (int j = 1; j < x - 1; j++) {
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double sx = (alpha[i * x + j] * timestep) / (dx * dx);
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double sy = (alpha[i * x + j] * timestep) / (dy * dy);
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tripletList.push_back(T(A_line, i * x + j, (1. + 2. * sx + 2. * sy)));
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std::cout << sx << std::endl;
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tripletList.push_back(T(A_line, (i - 1) * x + j, sy));
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tripletList.push_back(T(A_line, (i + 1) * x + j, sy));
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tripletList.push_back(T(A_line, i * x + (j + 1), sx));
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tripletList.push_back(T(A_line, i * x + (j - 1), sx));
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b[A_line] = -c[i * x + j];
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A_line++;
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}
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}
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std::cout << b << std::endl;
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Eigen::SparseMatrix<double> A(size, x * y);
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A.setFromTriplets(tripletList.begin(), tripletList.end());
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Eigen::SparseQR<Eigen::SparseMatrix<double>, Eigen::COLAMDOrdering<int>>
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solver;
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// Eigen::SparseLU<Eigen::SparseMatrix<double>, Eigen::COLAMDOrdering<int>>
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// solver;
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solver.analyzePattern(A);
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solver.factorize(A);
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std::cout << A << std::endl;
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std::cout << solver.lastErrorMessage() << std::endl;
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x_out = solver.solve(b);
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std::cout << x_out << std::endl;
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}
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