X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=blobdiff_plain;f=ginac%2Finifcns.cpp;h=0ee9b2737fd30ef8b31fe39dcb965f887ee114b8;hb=c5ca06e3a25226684028dec4bd8cba0833998be6;hp=b55261eb1a0072939b0a1bb43a2a317d681778ec;hpb=444d1e293d87b78f0497a55c6a4dabad010f5b62;p=ginac.git

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index b55261eb..0ee9b273 100644
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -475,15 +475,15 @@ ex lsolve(const ex &eqns, const ex &symbols)
 		for (unsigned c=0; c<symbols.nops(); c++) {
 			ex co = eq.coeff(ex_to_symbol(symbols.op(c)),1);
 			linpart -= co*symbols.op(c);
-			sys.set(r,c,co);
+			sys(r,c) = co;
 		}
 		linpart = linpart.expand();
-		rhs.set(r,0,-linpart);
+		rhs(r,0) = -linpart;
 	}
 	
 	// test if system is linear and fill vars matrix
 	for (unsigned i=0; i<symbols.nops(); i++) {
-		vars.set(i,0,symbols.op(i));
+		vars(i,0) = symbols.op(i);
 		if (sys.has(symbols.op(i)))
 			throw(std::logic_error("lsolve: system is not linear"));
 		if (rhs.has(symbols.op(i)))
@@ -509,18 +509,109 @@ ex lsolve(const ex &eqns, const ex &symbols)
 	return sollist;
 }
 
-/** non-commutative power. */
-ex ncpow(const ex & basis, unsigned exponent)
+// Symmetrize/antisymmetrize over a vector of objects
+static ex symm(const ex & e, exvector::const_iterator first, exvector::const_iterator last, bool asymmetric)
 {
-	if (exponent == 0)
-		return _ex1();
+	// Need at least 2 objects for this operation
+	int num = last - first;
+	if (num < 2)
+		return e;
+
+	// Transform object vector to a list
+	exlist iv_lst;
+	iv_lst.insert(iv_lst.begin(), first, last);
+	lst orig_lst(iv_lst, true);
+
+	// Create index vectors for permutation
+	unsigned *iv = new unsigned[num], *iv2;
+	for (unsigned i=0; i<num; i++)
+		iv[i] = i;
+	iv2 = (asymmetric ? new unsigned[num] : NULL);
+
+	// Loop over all permutations (the first permutation, which is the
+	// identity, is unrolled)
+	ex sum = e;
+	while (std::next_permutation(iv, iv + num)) {
+		lst new_lst;
+		for (unsigned i=0; i<num; i++)
+			new_lst.append(orig_lst.op(iv[i]));
+		ex term = e.subs(orig_lst, new_lst);
+		if (asymmetric) {
+			memcpy(iv2, iv, num * sizeof(unsigned));
+			term *= permutation_sign(iv2, iv2 + num);
+		}
+		sum += term;
+	}
+
+	delete[] iv;
+	delete[] iv2;
+
+	return sum / factorial(numeric(num));
+}
+
+ex symmetrize(const ex & e, exvector::const_iterator first, exvector::const_iterator last)
+{
+	return symm(e, first, last, false);
+}
+
+ex antisymmetrize(const ex & e, exvector::const_iterator first, exvector::const_iterator last)
+{
+	return symm(e, first, last, true);
+}
 
+ex symmetrize_cyclic(const ex & e, exvector::const_iterator first, exvector::const_iterator last)
+{
+	// Need at least 2 objects for this operation
+	int num = last - first;
+	if (num < 2)
+		return e;
+
+	// Transform object vector to a list
+	exlist iv_lst;
+	iv_lst.insert(iv_lst.begin(), first, last);
+	lst orig_lst(iv_lst, true);
+	lst new_lst = orig_lst;
+
+	// Loop over all cyclic permutations (the first permutation, which is
+	// the identity, is unrolled)
+	ex sum = e;
+	for (unsigned i=0; i<num-1; i++) {
+		ex perm = new_lst.op(0);
+		new_lst.remove_first().append(perm);
+		sum += e.subs(orig_lst, new_lst);
+	}
+	return sum / num;
+}
+
+/** Symmetrize expression over a list of objects (symbols, indices). */
+ex ex::symmetrize(const lst & l) const
+{
 	exvector v;
-	v.reserve(exponent);
-	for (unsigned i=0; i<exponent; ++i)
-		v.push_back(basis);
+	v.reserve(l.nops());
+	for (unsigned i=0; i<l.nops(); i++)
+		v.push_back(l.op(i));
+	return symm(*this, v.begin(), v.end(), false);
+}
 
-	return ncmul(v, true);
+/** Antisymmetrize expression over a list of objects (symbols, indices). */
+ex ex::antisymmetrize(const lst & l) const
+{
+	exvector v;
+	v.reserve(l.nops());
+	for (unsigned i=0; i<l.nops(); i++)
+		v.push_back(l.op(i));
+	return symm(*this, v.begin(), v.end(), true);
+}
+
+/** Symmetrize expression by cyclic permutation over a list of objects
+ *  (symbols, indices). */
+ex ex::symmetrize_cyclic(const lst & l) const
+{
+	exvector v;
+	v.reserve(l.nops());
+	for (unsigned i=0; i<l.nops(); i++)
+		v.push_back(l.op(i));
+	return GiNaC::symmetrize_cyclic(*this, v.begin(), v.end());
 }
 
 /** Force inclusion of functions from initcns_gamma and inifcns_zeta