Commit ac063d4e authored by Erik Strand's avatar Erik Strand

Switch to periodic boundary conditions

parent 832649ce
......@@ -78,7 +78,7 @@ void GlutGrapher::display() const {
//..................................................................................................
void GlutGrapher::idle() {
bool const wait_to_start = true;
bool const wait_to_start = false;
if (wait_to_start && frame_ == 0) {
std::cout << "Press enter to start a 5 second countdown" << std::endl;
do {} while (std::cin.get() != '\n');
......
......@@ -12,12 +12,18 @@ void mouse(int, int, int, int) { exit(0); }
//--------------------------------------------------------------------------------------------------
SparseMatrix<Scalar> d_x_first_order(int32_t const dim) {
return MatrixBuilder(dim).stripe(0, -1).stripe(1, 1);
// stripe(0, -1) means add a stripe of -1s on the diagonal
// stripe(1, 1) means add a stripe of 1s one above the diagonal
// element(dim - 1, 0, 1) means add a single 1 at row dim - 1 and column 0
return MatrixBuilder(dim).stripe(0, -1).stripe(1, 1).element(dim - 1, 0, 1);
}
//--------------------------------------------------------------------------------------------------
SparseMatrix<Scalar> d_x2_first_order(int32_t const dim) {
return MatrixBuilder(dim).stripe(-1, 1).stripe(0, -2).stripe(1, 1);
return MatrixBuilder(dim)
.stripe(-1, 1).element(0, dim - 1, 1)
.stripe(0, -2)
.stripe(1, 1).element(dim - 1, 0, 1);
}
//--------------------------------------------------------------------------------------------------
......@@ -49,7 +55,7 @@ int main(int, char**) {
Scalar const alpha = advection_coefficient * h / d;
Scalar const delta = diffusion_coefficient * h / (d * d);
// transport matrices (assumes dirichlet boundary conditions identically zero)
// transport matrices
SparseMatrix<Scalar> const advection_matrix = alpha * d_x_first_order(dim);
SparseMatrix<Scalar> const diffusion_matrix = delta * d_x2_first_order(dim);
SparseMatrix<Scalar> const reaction_matrix = h * diagonal_ones(dim) * reaction_coefficients.asDiagonal();
......
......@@ -15,6 +15,12 @@ MatrixBuilder& MatrixBuilder::stripe(int32_t k, Scalar value) {
return *this;
}
//..................................................................................................
MatrixBuilder& MatrixBuilder::element(int32_t row, int32_t col, Scalar value) {
triplets_.emplace_back(row, col, value);
return *this;
}
//..................................................................................................
MatrixBuilder::operator SparseMatrix<Scalar>() const {
SparseMatrix<Scalar> result(n_, n_);
......
......@@ -11,8 +11,11 @@ namespace simucene {
class MatrixBuilder {
public:
MatrixBuilder(int32_t n): n_(n) {}
// k = 0 means on the diagonal, 1 means one above the diagonal, -1 one below, etc.
MatrixBuilder& stripe(int32_t k, Scalar value);
MatrixBuilder& element(int32_t row, int32_t col, Scalar value);
operator SparseMatrix<Scalar>() const;
private:
......
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