Add graph references

references/igraph-1.0.1/examples/simple/igraph_pagerank.c

@@ -0,0 +1,39 @@
+
+#include <igraph.h>
+#include <float.h>
+
+int main(void) {
+    igraph_t graph;
+    igraph_vector_t pagerank;
+    igraph_real_t value;
+
+    /* Initialize the library. */
+    igraph_setup();
+
+    /* Create a directed graph */
+    igraph_kautz(&graph, 2, 3);
+
+    /* Initialize the vector where the results will be stored */
+    igraph_vector_init(&pagerank, 0);
+
+    igraph_pagerank(&graph, /* weights */ NULL,
+                    &pagerank, &value,
+            /* damping */ 0.85, IGRAPH_DIRECTED,
+                    igraph_vss_all(), IGRAPH_PAGERANK_ALGO_PRPACK,
+                    NULL /* not needed with PRPACK method */);
+
+    /* Check that the eigenvalue is 1, as expected. */
+    if (fabs(value - 1.0) > 32*DBL_EPSILON) {
+        fprintf(stderr, "PageRank failed to converge.\n");
+        return 1;
+    }
+
+    /* Output the result */
+    igraph_vector_print(&pagerank);
+
+    /* Destroy data structure when no longer needed */
+    igraph_vector_destroy(&pagerank);
+    igraph_destroy(&graph);
+
+    return 0;
+}