fixed a crash when constructing expressions like (dirac_ONE()+dirac_gamma5())*dirac_g...

diff --git a/ginac/clifford.cpp b/ginac/clifford.cpp
index e3c0ffd416d508d59255ef3334f73869e8d2edca..66ddc019ea5e76b0d10bfdb96d80e8718eb4c6b2 100644 (file)
--- a/ginac/clifford.cpp
+++ b/ginac/clifford.cpp
@@ -305,12 +305,6 @@ ex clifford::simplify_ncmul(const exvector & v) const
                }
        }
 
-       // Remove squares of gamma5
-       while (s.size() >= 2 && is_a<clifford>(s[0]) && is_a<clifford>(s[1]) && is_a<diracgamma5>(s[0].op(0)) && is_a<diracgamma5>(s[1].op(0))) {
-               s.erase(s.begin(), s.begin() + 2);
-               something_changed = true;
-       }
-
        // Remove equal adjacent gammas
        if (s.size() >= 2) {
                exvector::iterator it, itend = s.end() - 1;
@@ -319,7 +313,9 @@ ex clifford::simplify_ncmul(const exvector & v) const
                        ex & b = it[1];
                        if (!is_a<clifford>(a) || !is_a<clifford>(b))
                                continue;
-                       if (is_a<diracgamma>(a.op(0)) && is_a<diracgamma>(b.op(0))) {
+                       bool a_is_diracgamma = is_a<diracgamma>(a.op(0));
+                       bool b_is_diracgamma = is_a<diracgamma>(b.op(0));
+                       if (a_is_diracgamma && b_is_diracgamma) {
                                const ex & ia = a.op(1);
                                const ex & ib = b.op(1);
                                if (ia.is_equal(ib)) { // gamma~alpha gamma~alpha -> g~alpha~alpha
@@ -327,7 +323,12 @@ ex clifford::simplify_ncmul(const exvector & v) const
                                        b = dirac_ONE(representation_label);
                                        something_changed = true;
                                }
-                       } else if (!is_a<diracgamma>(a.op(0)) && !is_a<diracgamma>(b.op(0))) {
+                       } else if (is_a<diracgamma5>(a.op(0)) && is_a<diracgamma5>(b.op(0))) {
+                               // Remove squares of gamma5
+                               a = dirac_ONE(representation_label);
+                               b = dirac_ONE(representation_label);
+                               something_changed = true;
+                       } else if (!a_is_diracgamma && !b_is_diracgamma) {
                                const ex & ba = a.op(0);
                                const ex & bb = b.op(0);
                                if (ba.is_equal(bb)) { // a\ a\ -> a^2