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#include "network.hpp"
class nanException: public std::exception
{
virtual const char* what() const throw()
{
return "The linear problem returned NaN.";
}
} nanex;
class nofuseException: public std::exception
{
virtual const char* what() const throw()
{
return "No valid fuse was available to break.";
}
} nofuseex;
network::network(const graph& G, cholmod_common *c) : c(c), G(G), fuses(G.edges.size(), false), thresholds(G.edges.size(), 1) {
b = CHOL_F(zeros)(G.vertices.size(), 1, CHOLMOD_REAL, c);
for (unsigned i = 0; i < G.edges.size(); i++) {
double v0y = G.vertices[G.edges[i].v[0]].r.y;
double v1y = G.vertices[G.edges[i].v[1]].r.y;
if (G.edges[i].crossings[1]) {
bool ind = v0y < v1y ? 0 : 1;
((double *)b->x)[G.edges[i].v[ind]] += 1.0;
((double *)b->x)[G.edges[i].v[!ind]] -= 1.0;
}
}
unsigned nnz = G.vertices.size() + G.edges.size();
cholmod_triplet *t = CHOL_F(allocate_triplet)(G.vertices.size(), G.vertices.size(), nnz, 1, CHOLMOD_REAL, c);
for (unsigned i = 0; i < G.vertices.size(); i++) {
((CHOL_INT *)t->i)[i] = i;
((CHOL_INT *)t->j)[i] = i;
((double *)t->x)[i] = 0.0;
}
unsigned terms = G.vertices.size();
std::unordered_map<std::array<unsigned, 2>, unsigned> known_edges;
for (unsigned i = 0; i < G.edges.size(); i++) {
unsigned v0 = G.edges[i].v[0];
unsigned v1 = G.edges[i].v[1];
((double *)t->x)[v0]++;
((double *)t->x)[v1]++;
unsigned s0 = v0 < v1 ? v0 : v1;
unsigned s1 = v0 < v1 ? v1 : v0;
auto it = known_edges.find({s0, s1});
if (it == known_edges.end()) {
((CHOL_INT *)t->i)[terms] = s1;
((CHOL_INT *)t->j)[terms] = s0;
((double *)t->x)[terms] = -1.0;
known_edges[{s0, s1}] = terms;
terms++;
} else {
((double *)t->x)[it->second] -= 1.0;
}
}
((double *)t->x)[0]++;
t->nnz = terms;
cholmod_sparse *laplacian = CHOL_F(triplet_to_sparse)(t, terms, c);
CHOL_F(free_triplet)(&t, c);
factor = CHOL_F(analyze)(laplacian, c);
CHOL_F(factorize)(laplacian, factor, c);
CHOL_F(free_sparse)(&laplacian, c);
t = CHOL_F(allocate_triplet)(G.edges.size(), G.vertices.size(), 2 * G.edges.size(), 0, CHOLMOD_REAL, c);
t->nnz = 2 * G.edges.size();
for (unsigned i = 0; i < G.edges.size(); i++) {
((CHOL_INT *)t->i)[2 * i] = i;
((CHOL_INT *)t->j)[2 * i] = G.edges[i].v[0];
((double *)t->x)[2 * i] = 1.0;
((CHOL_INT *)t->i)[2 * i + 1] = i;
((CHOL_INT *)t->j)[2 * i + 1] = G.edges[i].v[1];
((double *)t->x)[2 * i + 1] = -1.0;
}
voltcurmat = CHOL_F(triplet_to_sparse)(t, 2 * G.edges.size(), c);
CHOL_F(free_triplet)(&t, c);
}
network::network(const network &other) : c(other.c), G(other.G), fuses(other.fuses), thresholds(other.thresholds) {
b = CHOL_F(copy_dense)(other.b, c);
factor = CHOL_F(copy_factor)(other.factor, c);
voltcurmat = CHOL_F(copy_sparse)(other.voltcurmat, c);
}
network::~network() {
CHOL_F(free_sparse)(&voltcurmat, c);
CHOL_F(free_dense)(&b, c);
CHOL_F(free_factor)(&factor, c);
}
void network::set_thresholds(double beta, std::mt19937& rng) {
if (beta == 0.0) {
/* zero beta doesn't make any sense computationally, we interpret it as "infinity" */
for (long double& threshold : thresholds) {
threshold = 1.0;
}
} else {
std::uniform_real_distribution<long double> d(0.0, 1.0);
for (long double& threshold : thresholds) {
threshold = std::numeric_limits<long double>::lowest();
while (threshold == std::numeric_limits<long double>::lowest()) {
threshold = logl(d(rng)) / (long double)beta;
}
}
}
}
void network::break_edge(unsigned e, bool unbreak) {
fuses[e] = !unbreak;
unsigned v0 = G.edges[e].v[0];
unsigned v1 = G.edges[e].v[1];
unsigned n = factor->n;
cholmod_sparse *update_mat = CHOL_F(allocate_sparse)(n, n, 2, true, true, 0, CHOLMOD_REAL, c);
unsigned s1, s2;
s1 = v0 < v1 ? v0 : v1;
s2 = v0 < v1 ? v1 : v0;
CHOL_INT *pp = (CHOL_INT *)update_mat->p;
CHOL_INT *ii = (CHOL_INT *)update_mat->i;
double *xx = (double *)update_mat->x;
for (unsigned i = 0; i <= s1; i++) {
pp[i] = 0;
}
for (unsigned i = s1 + 1; i <= n; i++) {
pp[i] = 2;
}
ii[0] = s1;
ii[1] = s2;
xx[0] = 1;
xx[1] = -1;
cholmod_sparse *perm_update_mat = CHOL_F(submatrix)(
update_mat, (CHOL_INT *)factor->Perm, factor->n, NULL, -1, true, true, c);
CHOL_F(updown)(unbreak, perm_update_mat, factor, c);
CHOL_F(free_sparse)(&perm_update_mat, c);
CHOL_F(free_sparse)(&update_mat, c);
double v0y = G.vertices[v0].r.y;
double v1y = G.vertices[v1].r.y;
if (G.edges[e].crossings[1]) {
bool ind = v0y < v1y ? unbreak : !unbreak;
((double *)b->x)[G.edges[e].v[ind]] -= 1.0;
((double *)b->x)[G.edges[e].v[!ind]] += 1.0;
}
}
current_info network::get_current_info() {
cholmod_dense *x = CHOL_F(solve)(CHOLMOD_A, factor, b, c);
if (((double *)x->x)[0] != ((double *)x->x)[0]) {
throw nanex;
}
cholmod_dense *y = CHOL_F(allocate_dense)(G.edges.size(), 1, G.edges.size(), CHOLMOD_REAL, c);
double alpha[2] = {1, 0};
double beta[2] = {0, 0};
CHOL_F(sdmult)(voltcurmat, 0, alpha, beta, x, y, c);
std::vector<double> currents(G.edges.size());
double total_current = 0;
for (int i = 0; i < G.edges.size(); i++) {
if (fuses[i]) {
currents[i] = 0;
} else {
currents[i] = ((double *)y->x)[i];
double v0y = G.vertices[G.edges[i].v[0]].r.y;
double v1y = G.vertices[G.edges[i].v[1]].r.y;
if (G.edges[i].crossings[1]) {
if (v0y > v1y) {
currents[i] += 1.0;
total_current += currents[i];
} else {
currents[i] -= 1.0;
total_current -= currents[i];
}
}
}
}
CHOL_F(free_dense)(&x, c);
CHOL_F(free_dense)(&y, c);
return {total_current, currents};
}
void network::fracture(hooks& m, double cutoff) {
m.pre_fracture(*this);
while (true) {
current_info ci = this->get_current_info();
if (ci.conductivity < cutoff * G.vertices.size()) {
break;
}
unsigned max_pos = UINT_MAX;
long double max_val = std::numeric_limits<long double>::lowest();
for (unsigned i = 0; i < G.edges.size(); i++) {
if (!fuses[i] && fabs(ci.currents[i]) > cutoff) {
long double val = logl(fabs(ci.currents[i])) - thresholds[i];
if (val > max_val) {
max_val = val;
max_pos = i;
}
}
}
if (max_pos == UINT_MAX) {
throw nofuseex;
}
this->break_edge(max_pos);
m.bond_broken(*this, ci, max_pos);
}
m.post_fracture(*this);
}
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