crappy but working version

src/gauss_seidel.c

@@ -49,8 +49,8 @@ double* gauss_seidel_pagerank(const SparseMatrix *matrix, double epsilon, double
         for (int i = N - 1; i >= 0; i--) {
             double result_mult = 0.0;
             double M_ii = 0.0;
-            for (int k = matrix->row_ptr[i]; k < matrix->row_ptr[i + 1]; k++) {
+            for (int k = matrix->col_ptr[i]; k < matrix->col_ptr[i + 1]; k++) {
-                int j = matrix->arcs[k].dest;
+                int j = matrix->arcs[k].origin;
                 double value = matrix->arcs[k].value;
 
                 if (j == i) {

src/main.c

@@ -10,6 +10,37 @@
 #include "time_helper.h"
 #include <sys/time.h>
 #include <string.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static double *values_for_sort;
+int cmp_desc(const void *a, const void *b) {
+    int ia = *(const int*)a;
+    int ib = *(const int*)b;
+    if (values_for_sort[ia] < values_for_sort[ib]) return  1;
+    if (values_for_sort[ia] > values_for_sort[ib]) return -1;
+    return 0;
+}
+
+void print_top_k(const char *name, double *pi, int n, int k) {
+    int *idx = malloc(n * sizeof(int));
+    if(!idx) {
+        fprintf(stderr, "malloc failed\n");
+        return;
+    }
+    for (int i = 0; i < n; i++) idx[i] = i;
+
+    values_for_sort = pi;
+    qsort(idx, n, sizeof(int), cmp_desc);
+
+    printf("Top %d entries of %s:\n", k, name);
+    for (int i = 0; i < k && i < n; i++) {
+        int node = idx[i];
+        printf("  %2d: node %d → %.8f\n", i+1, node, pi[node]);
+    }
+    free(idx);
+}
+
 
 void test_stationary_distribution(const char *path, double epsilon, double alpha) {
     struct timeval tvstart, tvend;
@@ -42,6 +73,11 @@ void test_stationary_distribution(const char *path, double epsilon, double alpha
     double diff = diff_norm_vector(pi_power, pi_new, matrix->num_nodes);
     printf("Difference norm Pagerank and Gauss-Seidel: %.16f\n", diff);
 
+    int n = matrix->num_nodes;
+    int k = 10;
+    print_top_k("pagerank (power)", pi_power, n, k);
+    print_top_k("pagerank (Gauss–Seidel)", pi_new,    n, k);
+
     free(pi_power);
     free(pi_new);
     free_sparse_matrix(matrix);

src/matrix_operation.c

@@ -53,14 +53,14 @@ void convert_to_stochastic(SparseMatrix *matrix) {
 
     // count non zero values
     for (int i = 0; i < matrix->num_arcs; i++) {
-        non_zero[matrix->arcs[i].dest] += matrix->arcs[i].value;
+        non_zero[matrix->arcs[i].origin] += matrix->arcs[i].value;
     }
 
     // normalize values
     for (int i = 0; i < matrix->num_arcs; i++) {
-        int dest = matrix->arcs[i].dest;
+        int origin = matrix->arcs[i].origin;
         double old_value = matrix->arcs[i].value;
-        matrix->arcs[i].value = old_value / (double)non_zero[dest];
+        matrix->arcs[i].value = old_value / (double)non_zero[origin];
     }
 
     free(non_zero);
@@ -69,6 +69,6 @@ void convert_to_stochastic(SparseMatrix *matrix) {
 int compare_arcs(const void *a, const void *b) {
     Arc *arc_a = (Arc *)a;
     Arc *arc_b = (Arc *)b;
-    return arc_a->origin - arc_b->origin;
+    return arc_a->dest - arc_b->dest;
 }
 

src/read_from_mtx.c

@@ -67,20 +67,20 @@ SparseMatrix* read_sparse_matrix_from_mtx(const char *filename) {
 
     parse_arcs(matrix, file);
 
-    // Sort arcs by origin
+    // Sort arcs by destination
     qsort(matrix->arcs, matrix->num_arcs, sizeof(Arc), compare_arcs);
-    // Build row_ptr
+    // Build col_ptr
-    matrix->row_ptr = (int *)malloc((matrix->num_nodes + 1) * sizeof(int));
+    matrix->col_ptr = (int *)malloc((matrix->num_nodes + 1) * sizeof(int));
-    int current_origin = 0;
+    int current_dest = 0;
-    matrix->row_ptr[0] = 0;
+    matrix->col_ptr[0] = 0;
     for (int k = 0; k < matrix->num_arcs; k++) {
-        while (matrix->arcs[k].origin > current_origin) {
+        while (matrix->arcs[k].dest > current_dest) {
-            current_origin++;
+            current_dest++;
-            matrix->row_ptr[current_origin] = k;
+            matrix->col_ptr[current_dest] = k;
         }
     }
-    for (int i = current_origin + 1; i <= matrix->num_nodes; i++) {
+    for (int i = current_dest + 1; i <= matrix->num_nodes; i++) {
-        matrix->row_ptr[i] = matrix->num_arcs;
+        matrix->col_ptr[i] = matrix->num_arcs;
     }
 
     fclose(file);

src/read_from_rb.c

@@ -99,21 +99,21 @@ SparseMatrix* read_sparse_matrix_from_rb(const char *filename) {
     }
 
 
-    // Sort arcs by origin
+    // Sort arcs by destination
     qsort(matrix->arcs, matrix->num_arcs, sizeof(Arc), compare_arcs);
 
-    // Build row_ptr
+    // Build col_ptr
-    matrix->row_ptr = (int *)malloc((matrix->num_nodes + 1) * sizeof(int));
+    matrix->col_ptr = (int *)malloc((matrix->num_nodes + 1) * sizeof(int));
-    int current_origin = 0;
+    int current_destination = 0;
-    matrix->row_ptr[0] = 0;
+    matrix->col_ptr[0] = 0;
     for (int k = 0; k < matrix->num_arcs; k++) {
-        while (matrix->arcs[k].origin > current_origin) {
+        while (matrix->arcs[k].dest > current_destination) {
-            current_origin++;
+            current_destination++;
-            matrix->row_ptr[current_origin] = k;
+            matrix->col_ptr[current_destination] = k;
         }
     }
-    for (int i = current_origin + 1; i <= matrix->num_nodes; i++) {
+    for (int i = current_destination + 1; i <= matrix->num_nodes; i++) {
-        matrix->row_ptr[i] = matrix->num_arcs;
+        matrix->col_ptr[i] = matrix->num_arcs;
     }
 
     free(col_ptr);

src/sparse_matrix.h

@@ -11,7 +11,7 @@ typedef struct {
     int num_nodes;
     int num_arcs;
     Arc *arcs;
-    int *row_ptr;
+    int *col_ptr;
 } SparseMatrix;
 
 void free_sparse_matrix(SparseMatrix *matrix);