- fixed a problem where (p\-m*ONE)*(p\-m*ONE) would be automatically simplified
[ginac.git] / ginac / clifford.cpp
index b5dff072b6601d2bb2893d7149e29eac50cdcf94..f6a511c4a3c8f21002b58daf1adf2b3e269759e7 100644 (file)
 #include "ncmul.h"
 #include "symbol.h"
 #include "numeric.h" // for I
+#include "symmetry.h"
 #include "lst.h"
 #include "relational.h"
+#include "mul.h"
 #include "print.h"
 #include "archive.h"
 #include "debugmsg.h"
@@ -82,17 +84,17 @@ clifford::clifford(const ex & b, unsigned char rl) : inherited(b), representatio
 clifford::clifford(const ex & b, const ex & mu, unsigned char rl) : inherited(b, mu), representation_label(rl)
 {
        debugmsg("clifford constructor from ex,ex", LOGLEVEL_CONSTRUCT);
-       GINAC_ASSERT(is_ex_of_type(mu, varidx));
+       GINAC_ASSERT(is_a<varidx>(mu));
        tinfo_key = TINFO_clifford;
 }
 
-clifford::clifford(unsigned char rl, const exvector & v, bool discardable) : inherited(indexed::unknown, v, discardable), representation_label(rl)
+clifford::clifford(unsigned char rl, const exvector & v, bool discardable) : inherited(sy_none(), v, discardable), representation_label(rl)
 {
        debugmsg("clifford constructor from unsigned char,exvector", LOGLEVEL_CONSTRUCT);
        tinfo_key = TINFO_clifford;
 }
 
-clifford::clifford(unsigned char rl, exvector * vp) : inherited(indexed::unknown, vp), representation_label(rl)
+clifford::clifford(unsigned char rl, exvector * vp) : inherited(sy_none(), vp), representation_label(rl)
 {
        debugmsg("clifford constructor from unsigned char,exvector *", LOGLEVEL_CONSTRUCT);
        tinfo_key = TINFO_clifford;
@@ -122,12 +124,12 @@ DEFAULT_ARCHIVING(diracgamma)
 DEFAULT_ARCHIVING(diracgamma5)
 
 //////////
-// functions overriding virtual functions from bases classes
+// functions overriding virtual functions from base classes
 //////////
 
 int clifford::compare_same_type(const basic & other) const
 {
-       GINAC_ASSERT(other.tinfo() == TINFO_clifford);
+       GINAC_ASSERT(is_of_type(other, clifford));
        const clifford &o = static_cast<const clifford &>(other);
 
        if (representation_label != o.representation_label) {
@@ -138,6 +140,34 @@ int clifford::compare_same_type(const basic & other) const
        return inherited::compare_same_type(other);
 }
 
+bool clifford::match_same_type(const basic & other) const
+{
+       GINAC_ASSERT(is_of_type(other, clifford));
+       const clifford &o = static_cast<const clifford &>(other);
+
+       return representation_label == o.representation_label;
+}
+
+void clifford::print(const print_context & c, unsigned level = 0) const
+{
+       if (!is_a<diracgamma5>(seq[0]) && !is_a<diracgamma>(seq[0]) && !is_a<diracone>(seq[0])) {
+
+               // dirac_slash() object is printed differently
+               if (is_a<print_tree>(c))
+                       inherited::print(c, level);
+               else if (is_a<print_latex>(c)) {
+                       c.s << "{";
+                       seq[0].print(c, level);
+                       c.s << "\\hspace{-1.0ex}/}";
+               } else {
+                       seq[0].print(c, level);
+                       c.s << "\\";
+               }
+
+       } else
+               inherited::print(c, level);
+}
+
 DEFAULT_COMPARE(diracone)
 DEFAULT_COMPARE(diracgamma)
 DEFAULT_COMPARE(diracgamma5)
@@ -146,17 +176,33 @@ DEFAULT_PRINT_LATEX(diracone, "ONE", "\\mathbb{1}")
 DEFAULT_PRINT_LATEX(diracgamma, "gamma", "\\gamma")
 DEFAULT_PRINT_LATEX(diracgamma5, "gamma5", "{\\gamma^5}")
 
+/** This function decomposes gamma~mu -> (1, mu) and a\ -> (a.ix, ix) */
+static void base_and_index(const ex & c, ex & b, ex & i)
+{
+       GINAC_ASSERT(is_a<clifford>(c));
+       GINAC_ASSERT(c.nops() == 2);
+
+       if (is_a<diracgamma>(c.op(0))) { // proper dirac gamma object
+               i = c.op(1);
+               b = _ex1();
+       } else { // slash object, generate new dummy index
+               varidx ix((new symbol)->setflag(status_flags::dynallocated), ex_to<idx>(c.op(1)).get_dim());
+               b = indexed(c.op(0), ix.toggle_variance());
+               i = ix;
+       }
+}
+
 /** Contraction of a gamma matrix with something else. */
 bool diracgamma::contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const
 {
-       GINAC_ASSERT(is_ex_of_type(*self, clifford));
-       GINAC_ASSERT(is_ex_of_type(*other, indexed));
-       GINAC_ASSERT(is_ex_of_type(self->op(0), diracgamma));
-       unsigned char rl = ex_to_clifford(*self).get_representation_label();
+       GINAC_ASSERT(is_a<clifford>(*self));
+       GINAC_ASSERT(is_a<indexed>(*other));
+       GINAC_ASSERT(is_a<diracgamma>(self->op(0)));
+       unsigned char rl = ex_to<clifford>(*self).get_representation_label();
 
-       if (is_ex_of_type(*other, clifford)) {
+       if (is_a<clifford>(*other)) {
 
-               ex dim = ex_to_idx(self->op(1)).get_dim();
+               ex dim = ex_to<idx>(self->op(1)).get_dim();
 
                // gamma~mu gamma.mu = dim ONE
                if (other - self == 1) {
@@ -166,18 +212,33 @@ bool diracgamma::contract_with(exvector::iterator self, exvector::iterator other
 
                // gamma~mu gamma~alpha gamma.mu = (2-dim) gamma~alpha
                } else if (other - self == 2
-                       && is_ex_of_type(self[1], clifford)) {
+                       && is_a<clifford>(self[1])) {
                        *self = 2 - dim;
                        *other = _ex1();
                        return true;
 
                // gamma~mu gamma~alpha gamma~beta gamma.mu = 4 g~alpha~beta + (dim-4) gamam~alpha gamma~beta
                } else if (other - self == 3
-                       && is_ex_of_type(self[1], clifford)
-                       && is_ex_of_type(self[2], clifford)) {
-                       *self = 4 * lorentz_g(self[1].op(1), self[2].op(1)) * dirac_ONE(rl) + (dim - 4) * self[1] * self[2];
+                       && is_a<clifford>(self[1])
+                       && is_a<clifford>(self[2])) {
+                       ex b1, i1, b2, i2;
+                       base_and_index(self[1], b1, i1);
+                       base_and_index(self[2], b2, i2);
+                       *self = 4 * lorentz_g(i1, i2) * b1 * b2 * dirac_ONE(rl) + (dim - 4) * self[1] * self[2];
+                       self[1] = _ex1();
+                       self[2] = _ex1();
+                       *other = _ex1();
+                       return true;
+
+               // gamma~mu gamma~alpha gamma~beta gamma~delta gamma.mu = -2 gamma~delta gamma~beta gamma~alpha - (dim-4) gamam~alpha gamma~beta gamma~delta
+               } else if (other - self == 4
+                       && is_a<clifford>(self[1])
+                       && is_a<clifford>(self[2])
+                       && is_a<clifford>(self[3])) {
+                       *self = -2 * self[3] * self[2] * self[1] - (dim - 4) * self[1] * self[2] * self[3];
                        self[1] = _ex1();
                        self[2] = _ex1();
+                       self[3] = _ex1();
                        *other = _ex1();
                        return true;
 
@@ -187,9 +248,9 @@ bool diracgamma::contract_with(exvector::iterator self, exvector::iterator other
                } else {
                        exvector::iterator it = self + 1, next_to_last = other - 1;
                        while (it != other) {
-                               if (!is_ex_of_type(*it, clifford))
+                               if (!is_a<clifford>(*it))
                                        return false;
-                               it++;
+                               ++it;
                        }
 
                        it = self + 1;
@@ -220,7 +281,7 @@ ex clifford::simplify_ncmul(const exvector & v) const
        // Remove superfluous ONEs
        exvector::const_iterator cit = v.begin(), citend = v.end();
        while (cit != citend) {
-               if (!is_ex_of_type(cit->op(0), diracone))
+               if (!is_a<diracone>(cit->op(0)))
                        s.push_back(*cit);
                cit++;
        }
@@ -235,47 +296,57 @@ ex clifford::simplify_ncmul(const exvector & v) const
                        exvector::iterator it = next_to_last;
                        while (true) {
                                exvector::iterator it2 = it + 1;
-                               if (!is_ex_of_type(it->op(0), diracgamma5) && is_ex_of_type(it2->op(0), diracgamma5)) {
+                               if (!is_a<diracgamma5>(it->op(0)) && is_a<diracgamma5>(it2->op(0))) {
                                        it->swap(*it2);
                                        sign = -sign;
                                        something_changed = true;
                                }
                                if (it == first)
                                        break;
-                               it--;
+                               --it;
                        }
                        if (next_to_last == first)
                                break;
-                       next_to_last--;
+                       --next_to_last;
                }
        }
 
        // Remove squares of gamma5
-       while (s.size() >= 2 && is_ex_of_type(s[0].op(0), diracgamma5) && is_ex_of_type(s[1].op(0), diracgamma5)) {
+       while (s.size() >= 2 && 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 = s.begin(), itend = s.end() - 1;
-               while (it != itend) {
+               exvector::iterator it, itend = s.end() - 1;
+               for (it = s.begin(); it != itend; ++it) {
+                       if (!is_a<clifford>(it[0]))
+                               continue;
                        ex & a = it[0];
                        ex & b = it[1];
-                       if (is_ex_of_type(a.op(0), diracgamma) && is_ex_of_type(b.op(0), diracgamma)) {
+                       if (is_a<diracgamma>(a.op(0)) && is_a<diracgamma>(b.op(0))) {
                                const ex & ia = a.op(1);
                                const ex & ib = b.op(1);
-                               if (ia.is_equal(ib)) {
+                               if (ia.is_equal(ib)) { // gamma~alpha gamma~alpha -> g~alpha~alpha
                                        a = lorentz_g(ia, ib);
                                        b = dirac_ONE(representation_label);
                                        something_changed = true;
                                }
+                       } else if (!is_a<diracgamma>(a.op(0)) && !is_a<diracgamma>(b.op(0))) {
+                               const ex & ba = a.op(0);
+                               const ex & bb = b.op(0);
+                               if (ba.is_equal(bb)) { // a\ a\ -> a^2
+                                       varidx ix((new symbol)->setflag(status_flags::dynallocated), ex_to<idx>(a.op(1)).get_dim());
+                                       a = indexed(ba, ix) * indexed(bb, ix.toggle_variance());
+                                       b = dirac_ONE(representation_label);
+                                       something_changed = true;
+                               }
                        }
-                       it++;
                }
        }
 
-       if (s.size() == 0)
+       if (s.empty())
                return clifford(diracone(), representation_label) * sign;
        if (something_changed)
                return nonsimplified_ncmul(s) * sign;
@@ -304,7 +375,7 @@ ex dirac_ONE(unsigned char rl)
 
 ex dirac_gamma(const ex & mu, unsigned char rl)
 {
-       if (!is_ex_of_type(mu, varidx))
+       if (!is_a<varidx>(mu))
                throw(std::invalid_argument("index of Dirac gamma must be of type varidx"));
 
        return clifford(diracgamma(), mu, rl);
@@ -327,8 +398,10 @@ ex dirac_gamma7(unsigned char rl)
 
 ex dirac_slash(const ex & e, const ex & dim, unsigned char rl)
 {
-       varidx mu((new symbol)->setflag(status_flags::dynallocated), dim);
-       return indexed(e, mu.toggle_variance()) * dirac_gamma(mu, rl);
+       // Slashed vectors are actually stored as a clifford object with the
+       // vector as its base expression and a (dummy) index that just serves
+       // for storing the space dimensionality
+       return clifford(e, varidx(0, dim), rl);
 }
 
 /** Check whether a given tinfo key (as returned by return_type_tinfo()
@@ -345,31 +418,58 @@ static bool is_clifford_tinfo(unsigned ti)
        return (ti & ~0xff) == TINFO_clifford;
 }
 
+/** Take trace of a string of an even number of Dirac gammas given a vector
+ *  of indices. */
+static ex trace_string(exvector::const_iterator ix, unsigned num)
+{
+       // Tr gamma.mu gamma.nu = 4 g.mu.nu
+       if (num == 2)
+               return lorentz_g(ix[0], ix[1]);
+
+       // Tr gamma.mu gamma.nu gamma.rho gamma.sig = 4 (g.mu.nu g.rho.sig + g.nu.rho g.mu.sig - g.mu.rho g.nu.sig
+       else if (num == 4)
+               return lorentz_g(ix[0], ix[1]) * lorentz_g(ix[2], ix[3])
+                    + lorentz_g(ix[1], ix[2]) * lorentz_g(ix[0], ix[3])
+                    - lorentz_g(ix[0], ix[2]) * lorentz_g(ix[1], ix[3]);
+
+       // Traces of 6 or more gammas are computed recursively:
+       // Tr gamma.mu1 gamma.mu2 ... gamma.mun =
+       //   + g.mu1.mu2 * Tr gamma.mu3 ... gamma.mun
+       //   - g.mu1.mu3 * Tr gamma.mu2 gamma.mu4 ... gamma.mun
+       //   + g.mu1.mu4 * Tr gamma.mu3 gamma.mu3 gamma.mu5 ... gamma.mun
+       //   - ...
+       //   + g.mu1.mun * Tr gamma.mu2 ... gamma.mu(n-1)
+       exvector v(num - 2);
+       int sign = 1;
+       ex result;
+       for (unsigned i=1; i<num; i++) {
+               for (unsigned n=1, j=0; n<num; n++) {
+                       if (n == i)
+                               continue;
+                       v[j++] = ix[n];
+               }
+               result += sign * lorentz_g(ix[0], ix[i]) * trace_string(v.begin(), num-2);
+               sign = -sign;
+       }
+       return result;
+}
+
 ex dirac_trace(const ex & e, unsigned char rl, const ex & trONE)
 {
-       if (is_ex_of_type(e, clifford)) {
+       if (is_a<clifford>(e)) {
 
-               if (ex_to_clifford(e).get_representation_label() == rl
-                && is_ex_of_type(e.op(0), diracone))
+               if (ex_to<clifford>(e).get_representation_label() == rl
+                && is_a<diracone>(e.op(0)))
                        return trONE;
                else
                        return _ex0();
 
-       } else if (is_ex_exactly_of_type(e, add)) {
-
-               // Trace of sum = sum of traces
-               ex sum = _ex0();
-               for (unsigned i=0; i<e.nops(); i++)
-                       sum += dirac_trace(e.op(i), rl, trONE);
-               return sum;
-
        } else if (is_ex_exactly_of_type(e, mul)) {
 
                // Trace of product: pull out non-clifford factors
                ex prod = _ex1();
                for (unsigned i=0; i<e.nops(); i++) {
                        const ex &o = e.op(i);
-                       unsigned ti = o.return_type_tinfo();
                        if (is_clifford_tinfo(o.return_type_tinfo(), rl))
                                prod *= dirac_trace(o, rl, trONE);
                        else
@@ -384,11 +484,11 @@ ex dirac_trace(const ex & e, unsigned char rl, const ex & trONE)
 
                // Expand product, if necessary
                ex e_expanded = e.expand();
-               if (!is_ex_of_type(e_expanded, ncmul))
+               if (!is_a<ncmul>(e_expanded))
                        return dirac_trace(e_expanded, rl, trONE);
 
                // gamma5 gets moved to the front so this check is enough
-               bool has_gamma5 = is_ex_of_type(e.op(0).op(0), diracgamma5);
+               bool has_gamma5 = is_a<diracgamma5>(e.op(0).op(0));
                unsigned num = e.nops();
 
                if (has_gamma5) {
@@ -399,61 +499,49 @@ ex dirac_trace(const ex & e, unsigned char rl, const ex & trONE)
                                return _ex0();
 
                        // Tr gamma5 gamma.mu gamma.nu gamma.rho gamma.sigma = 4I * epsilon(mu, nu, rho, sigma)
-                       if (num == 5)
-                               return trONE * I * eps0123(e.op(1).op(1), e.op(2).op(1), e.op(3).op(1), e.op(4).op(1));
-
-                       // Tr gamma5 gamma.mu1 gamma.mu2 gamma.mu3 gamma.mu4 gamma.mu5 gamma.mu6 = ...
-                       if (num == 7) {
-                               ex i1 = e.op(1).op(1), i2 = e.op(2).op(1),
-                                  i3 = e.op(3).op(1), i4 = e.op(4).op(1),
-                                  i5 = e.op(5).op(1), i6 = e.op(6).op(1);
-                               return trONE * I * (lorentz_g(i1, i2) * eps0123(i3, i4, i5, i6)
-                                                 - lorentz_g(i1, i3) * eps0123(i2, i4, i5, i6)
-                                                 + lorentz_g(i1, i4) * eps0123(i2, i3, i5, i6)
-                                                 - lorentz_g(i1, i5) * eps0123(i2, i3, i4, i6)
-                                                 + lorentz_g(i1, i6) * eps0123(i2, i3, i4, i5)
-                                                 + lorentz_g(i2, i3) * eps0123(i1, i4, i5, i6)
-                                                 - lorentz_g(i2, i4) * eps0123(i1, i3, i5, i6)
-                                                 + lorentz_g(i2, i5) * eps0123(i1, i3, i4, i6)
-                                                 - lorentz_g(i2, i6) * eps0123(i1, i3, i4, i5)
-                                                 + lorentz_g(i3, i4) * eps0123(i1, i2, i5, i6)
-                                                 - lorentz_g(i3, i5) * eps0123(i1, i2, i4, i6)
-                                                 + lorentz_g(i3, i6) * eps0123(i1, i2, i4, i5)
-                                                 + lorentz_g(i4, i5) * eps0123(i1, i2, i3, i6)
-                                                 - lorentz_g(i4, i6) * eps0123(i1, i2, i3, i5)
-                                                 + lorentz_g(i5, i6) * eps0123(i1, i2, i3, i4));
+                       if (num == 5) {
+                               ex b1, i1, b2, i2, b3, i3, b4, i4;
+                               base_and_index(e.op(1), b1, i1);
+                               base_and_index(e.op(2), b2, i2);
+                               base_and_index(e.op(3), b3, i3);
+                               base_and_index(e.op(4), b4, i4);
+                               return trONE * I * (eps0123(i1, i2, i3, i4) * b1 * b2 * b3 * b4).simplify_indexed();
                        }
 
-                       // Tr gamma5 S_2k =
+                       // Tr gamma5 S_2k =
                        //   I/4! * epsilon0123.mu1.mu2.mu3.mu4 * Tr gamma.mu1 gamma.mu2 gamma.mu3 gamma.mu4 S_2k
+                       exvector ix(num-1), bv(num-1);
+                       for (unsigned i=1; i<num; i++)
+                               base_and_index(e.op(i), bv[i-1], ix[i-1]);
+                       num--;
+                       int *iv = new int[num];
                        ex result;
-                       for (int i=1; i<num-3; i++) {
-                               ex idx1 = e.op(i).op(1);
-                               for (int j=i+1; j<num-2; j++) {
-                                       ex idx2 = e.op(j).op(1);
-                                       for (int k=j+1; k<num-1; k++) {
-                                               ex idx3 = e.op(k).op(1);
-                                               for (int l=k+1; l<num; l++) {
-                                                       ex idx4 = e.op(l).op(1);
-                                                       vector<int> iv;
-                                                       iv.reserve(num-1);
+                       for (unsigned i=0; i<num-3; i++) {
+                               ex idx1 = ix[i];
+                               for (unsigned j=i+1; j<num-2; j++) {
+                                       ex idx2 = ix[j];
+                                       for (unsigned k=j+1; k<num-1; k++) {
+                                               ex idx3 = ix[k];
+                                               for (unsigned l=k+1; l<num; l++) {
+                                                       ex idx4 = ix[l];
+                                                       iv[0] = i; iv[1] = j; iv[2] = k; iv[3] = l;
                                                        exvector v;
-                                                       v.reserve(num-1);
-                                                       iv.push_back(i); iv.push_back(j); iv.push_back(k); iv.push_back(l);
-                                                       for (int n=1; n<num; n++) {
+                                                       v.reserve(num - 4);
+                                                       for (unsigned n=0, t=4; n<num; n++) {
                                                                if (n == i || n == j || n == k || n == l)
                                                                        continue;
-                                                               iv.push_back(n);
-                                                               v.push_back(e.op(n));
+                                                               iv[t++] = n;
+                                                               v.push_back(ix[n]);
                                                        }
-                                                       int sign = permutation_sign(iv.begin(), iv.end());
+                                                       int sign = permutation_sign(iv, iv + num);
                                                        result += sign * eps0123(idx1, idx2, idx3, idx4)
-                                                               * dirac_trace(ncmul(v, true), rl, trONE);
+                                                               * trace_string(v.begin(), num - 4);
                                                }
                                        }
                                }
                        }
-                       return result * I;
+                       delete[] iv;
+                       return trONE * I * result * mul(bv);
 
                } else { // no gamma5
 
@@ -462,40 +550,28 @@ ex dirac_trace(const ex & e, unsigned char rl, const ex & trONE)
                                return _ex0();
 
                        // Tr gamma.mu gamma.nu = 4 g.mu.nu
-                       if (num == 2)
-                               return trONE * lorentz_g(e.op(0).op(1), e.op(1).op(1));
-
-                       // Tr gamma.mu gamma.nu gamma.rho gamma.sig = 4 (g.mu.nu g.rho.sig + g.nu.rho g.mu.sig - g.mu.rho g.nu.sig
-                       if (num == 4)
-                               return trONE * (lorentz_g(e.op(0).op(1), e.op(1).op(1)) * lorentz_g(e.op(2).op(1), e.op(3).op(1))
-                                             + lorentz_g(e.op(1).op(1), e.op(2).op(1)) * lorentz_g(e.op(0).op(1), e.op(3).op(1))
-                                             - lorentz_g(e.op(0).op(1), e.op(2).op(1)) * lorentz_g(e.op(1).op(1), e.op(3).op(1)));
-
-                       // Traces of 6 or more gammas are computed recursively:
-                       // Tr gamma.mu1 gamma.mu2 ... gamma.mun =
-                       //   + g.mu1.mu2 * Tr gamma.mu3 ... gamma.mun
-                       //   - g.mu1.mu3 * Tr gamma.mu2 gamma.mu4 ... gamma.mun
-                       //   + g.mu1.mu4 * Tr gamma.mu3 gamma.mu3 gamma.mu5 ... gamma.mun
-                       //   - ...
-                       //   + g.mu1.mun * Tr gamma.mu2 ... gamma.mu(n-1)
-                       exvector v(num - 2);
-                       int sign = 1;
-                       const ex &ix1 = e.op(0).op(1);
-                       ex result;
-                       for (int i=1; i<num; i++) {
-                               for (int n=1, j=0; n<num; n++) {
-                                       if (n == i)
-                                               continue;
-                                       v[j++] = e.op(n);
-                               }
-                               result += sign * lorentz_g(ix1, e.op(i).op(1)) * dirac_trace(ncmul(v), rl, trONE);
-                               sign = -sign;
+                       if (num == 2) {
+                               ex b1, i1, b2, i2;
+                               base_and_index(e.op(0), b1, i1);
+                               base_and_index(e.op(1), b2, i2);
+                               return trONE * (lorentz_g(i1, i2) * b1 * b2).simplify_indexed();
                        }
-                       return result;
+
+                       exvector iv(num), bv(num);
+                       for (unsigned i=0; i<num; i++)
+                               base_and_index(e.op(i), bv[i], iv[i]);
+
+                       return trONE * (trace_string(iv.begin(), num) * mul(bv)).simplify_indexed();
                }
-       }
 
-       return _ex0();
+       } else if (e.nops() > 0) {
+
+               // Trace maps to all other container classes (this includes sums)
+               pointer_to_map_function_2args<unsigned char, const ex &> fcn(dirac_trace, rl, trONE);
+               return e.map(fcn);
+
+       } else
+               return _ex0();
 }
 
 ex canonicalize_clifford(const ex & e)
@@ -514,11 +590,11 @@ ex canonicalize_clifford(const ex & e)
 
                        // Expand product, if necessary
                        ex rhs_expanded = rhs.expand();
-                       if (!is_ex_of_type(rhs_expanded, ncmul)) {
+                       if (!is_a<ncmul>(rhs_expanded)) {
                                srl.let_op(i) = (lhs == canonicalize_clifford(rhs_expanded));
                                continue;
 
-                       } else if (!is_ex_of_type(rhs.op(0), clifford))
+                       } else if (!is_a<clifford>(rhs.op(0)))
                                continue;
 
                        exvector v;
@@ -526,14 +602,17 @@ ex canonicalize_clifford(const ex & e)
                        for (unsigned j=0; j<rhs.nops(); j++)
                                v.push_back(rhs.op(j));
 
-                       // Stupid bubble sort because we only want to swap adjacent gammas
+                       // Stupid recursive bubble sort because we only want to swap adjacent gammas
                        exvector::iterator it = v.begin(), next_to_last = v.end() - 1;
-                       if (is_ex_of_type(it->op(0), diracgamma5))
-                               it++;
+                       if (is_a<diracgamma5>(it->op(0)))
+                               ++it;
                        while (it != next_to_last) {
-                               if (it[0].op(1).compare(it[1].op(1)) > 0) {
+                               if (it[0].compare(it[1]) > 0) {
                                        ex save0 = it[0], save1 = it[1];
-                                       it[0] = lorentz_g(it[0].op(1), it[1].op(1));
+                                       ex b1, i1, b2, i2;
+                                       base_and_index(it[0], b1, i1);
+                                       base_and_index(it[1], b2, i2);
+                                       it[0] = (lorentz_g(i1, i2) * b1 * b2).simplify_indexed();
                                        it[1] = _ex2();
                                        ex sum = ncmul(v);
                                        it[0] = save1;
@@ -542,12 +621,12 @@ ex canonicalize_clifford(const ex & e)
                                        srl.let_op(i) = (lhs == canonicalize_clifford(sum));
                                        goto next_sym;
                                }
-                               it++;
+                               ++it;
                        }
 next_sym:      ;
                }
        }
-       return aux.subs(srl);
+       return aux.subs(srl).simplify_indexed();
 }
 
 } // namespace GiNaC