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Sam Hadow
2025-05-14 17:30:41 +02:00
parent 9e130fa992
commit 106125e049
2 changed files with 8 additions and 19 deletions
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17
src/main.c
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@@ -12,7 +12,6 @@
void test_stationary_distribution(const char *path) { void test_stationary_distribution(const char *path) {
struct timeval tvstart, tvend; struct timeval tvstart, tvend;
// Read and prepare the matrix
gettimeofday(&tvstart, NULL); gettimeofday(&tvstart, NULL);
SparseMatrix *matrix = read_sparse_matrix_from_mtx(path); SparseMatrix *matrix = read_sparse_matrix_from_mtx(path);
convert_to_stochastic(matrix); convert_to_stochastic(matrix);
@@ -22,32 +21,20 @@ void test_stationary_distribution(const char *path) {
double epsilon = 1e-10; double epsilon = 1e-10;
double alpha = 0.8; double alpha = 0.8;
// pagerank
gettimeofday(&tvstart, NULL); gettimeofday(&tvstart, NULL);
double *pi_power = pagerank(matrix, epsilon, alpha); double *pi_power = pagerank(matrix, epsilon, alpha);
gettimeofday(&tvend, NULL); gettimeofday(&tvend, NULL);
print_time_diff("Pagerank", &tvstart, &tvend); print_time_diff("Pagerank", &tvstart, &tvend);
// nable delta
gettimeofday(&tvstart, NULL); gettimeofday(&tvstart, NULL);
double *pi_new = gauss_seidel_pagerank(matrix, epsilon, alpha); double *pi_new = gauss_seidel_pagerank(matrix, epsilon, alpha);
gettimeofday(&tvend, NULL); gettimeofday(&tvend, NULL);
print_time_diff("Gauss Seidel algorithm", &tvstart, &tvend); print_time_diff("Gauss-Seidel:", &tvstart, &tvend);
// Compare results
double diff = diff_norm_vector(pi_power, pi_new, matrix->num_nodes); double diff = diff_norm_vector(pi_power, pi_new, matrix->num_nodes);
printf("Difference between power method and new algorithm: %.16f\n", diff); printf("Difference norm Pagerank and Gauss-Seidel: %.16f\n", diff);
for (int i = 0; i < 10; ++i) {
printf("pi_old: %.16f\n", pi_power[i]);
printf("pi_new: %.16f\n", pi_new[i]);
printf("\n");
}
// Clean up
free(pi_power); free(pi_power);
free(pi_new); free(pi_new);
free_sparse_matrix(matrix); free_sparse_matrix(matrix);

10
src/power_algorithm.c
View File

@@ -19,7 +19,6 @@ double* power_algorithm(const SparseMatrix *matrix, double epsilon) {
init_vector(pi, N, 1.0/(double)N); init_vector(pi, N, 1.0/(double)N);
pi2 = power_algorithm_step(matrix, pi); pi2 = power_algorithm_step(matrix, pi);
while (diff_norm_vector(pi, pi2, N)>epsilon) { while (diff_norm_vector(pi, pi2, N)>epsilon) {
printf("step\n");
memcpy(pi, pi2, vecsize); memcpy(pi, pi2, vecsize);
pi2 = power_algorithm_step(matrix, pi); pi2 = power_algorithm_step(matrix, pi);
} }
@@ -65,12 +64,15 @@ double* pagerank(const SparseMatrix *matrix, double epsilon, double alpha) {
pi = pi_new; pi = pi_new;
pi_new = malloc(vec_size); pi_new = malloc(vec_size);
if ((++iter)%1 == 0) { // if ((++iter)%1 == 0) {
printf("Iteration %d: diff = %.16f\n", iter, diff); // printf("Iteration %d: diff = %.16f\n", iter, diff);
} // }
++iter;
free(temp); free(temp);
} while (diff > epsilon); } while (diff > epsilon);
printf("Pagerank: %d Iterations\n", iter);
free(pi_new); free(pi_new);
free(f); free(f);
return pi; return pi;