X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?a=blobdiff_plain;f=ginac%2Finifcns.cpp;h=4d1c978b716a6b2c2ba456acd26a2d7dfcf66b02;hb=9161d9595342942ebaa532b6b068db94325d1ee7;hp=0daa97989abf8260202a0db99cfb572f576379ec;hpb=7cad9b41c97f0b042ba4af8080e82c8ad4804560;p=ginac.git

diff --git a/ginac/inifcns.cpp b/ginac/inifcns.cpp
index 0daa9798..4d1c978b 100644
--- a/ginac/inifcns.cpp
+++ b/ginac/inifcns.cpp
@@ -82,7 +82,8 @@ static ex csgn_eval(const ex & arg)
 	if (is_ex_exactly_of_type(arg, numeric))
 		return csgn(ex_to_numeric(arg));
 	
-	else if (is_ex_exactly_of_type(arg, mul)) {
+	else if (is_ex_of_type(arg, mul) &&
+	         is_ex_of_type(arg.op(arg.nops()-1),numeric)) {
 		numeric oc = ex_to_numeric(arg.op(arg.nops()-1));
 		if (oc.is_real()) {
 			if (oc > 0)
@@ -101,7 +102,7 @@ static ex csgn_eval(const ex & arg)
 				return -csgn(I*arg/oc).hold();
 		}
 	}
-   
+	
 	return csgn(arg).hold();
 }
 
@@ -474,15 +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)))
@@ -508,20 +509,63 @@ ex lsolve(const ex &eqns, const ex &symbols)
 	return sollist;
 }
 
-/** non-commutative power. */
-ex ncpower(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;
+
+	// Sort object vector, transform it into a list, and make a copy so we
+	// will know which objects get substituted for which
+	exlist iv_lst;
+	iv_lst.insert(iv_lst.begin(), first, last);
+	shaker_sort(iv_lst.begin(), iv_lst.end(), ex_is_less());
+	lst orig_lst(iv_lst);
+
+	// Loop over all permutations (the first permutation, which is the
+	// identity, is unrolled)
+	ex sum = e;
+	while (next_permutation(iv_lst.begin(), iv_lst.end(), ex_is_less())) {
+		ex term = e.subs(orig_lst, lst(iv_lst));
+		if (asymmetric) {
+			exlist test_lst = iv_lst;
+			term *= permutation_sign(test_lst.begin(), test_lst.end(), ex_is_less());
+		}
+		sum += term;
 	}
+	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);
+}
 
+/** 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,1);
+/** 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);
 }
 
 /** Force inclusion of functions from initcns_gamma and inifcns_zeta