Fix little missed optimization.

diff --git a/ginac/power.cpp b/ginac/power.cpp
index 28e5bd3a82acbef059c258882d22d44616319ede..7298d569946ee5ceb98e5a0dcf02fd1311a12506 100644 (file)
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -1097,7 +1097,7 @@ public:
  *  where n = p1+p2+...+pk, i.e. p is a partition of n.
  */
 const numeric
-multinomial_coefficient(const std::vector<int> p)
+multinomial_coefficient(const std::vector<int> & p)
 {
        numeric n = 0, d = 1;
        std::vector<int>::const_iterator it = p.begin(), itend = p.end();