fix bug #597: typo in sparse documentation
diff --git a/doc/TutorialSparse.dox b/doc/TutorialSparse.dox
index 98c9997..065edbf 100644
--- a/doc/TutorialSparse.dox
+++ b/doc/TutorialSparse.dox
@@ -290,9 +290,9 @@
\endcode
The second algorithm prunes on the fly the explicit zeros, or the values smaller than a given threshold. It is enabled and controlled through the prune() functions:
\code
-sm3 = (sm1 * sm2).prune(); // removes numerical zeros
-sm3 = (sm1 * sm2).prune(ref); // removes elements much smaller than ref
-sm3 = (sm1 * sm2).prune(ref,epsilon); // removes elements smaller than ref*epsilon
+sm3 = (sm1 * sm2).pruned(); // removes numerical zeros
+sm3 = (sm1 * sm2).pruned(ref); // removes elements much smaller than ref
+sm3 = (sm1 * sm2).pruned(ref,epsilon); // removes elements smaller than ref*epsilon
\endcode
- \b permutations. Finally, permutations can be applied to sparse matrices too: