3 * Interface to GiNaC's symmetry definitions. */
6 * GiNaC Copyright (C) 1999-2006 Johannes Gutenberg University Mainz, Germany
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
23 #ifndef __GINAC_SYMMETRY_H__
24 #define __GINAC_SYMMETRY_H__
36 /** This class describes the symmetry of a group of indices. These objects
37 * can be grouped into a tree to form complex mixed symmetries. */
38 class symmetry : public basic
40 friend class sy_is_less;
42 friend int canonicalize(exvector::iterator v, const symmetry &symm);
44 GINAC_DECLARE_REGISTERED_CLASS(symmetry, basic)
48 /** Type of symmetry */
50 none, /**< no symmetry properties */
51 symmetric, /**< totally symmetric */
52 antisymmetric, /**< totally antisymmetric */
53 cyclic /**< cyclic symmetry */
58 /** Create leaf node that represents one index. */
61 /** Create node with two children. */
62 symmetry(symmetry_type t, const symmetry &c1, const symmetry &c2);
64 // non-virtual functions in this class
66 /** Get symmetry type. */
67 symmetry_type get_type() const {return type;}
69 /** Set symmetry type. */
70 void set_type(symmetry_type t) {type = t;}
72 /** Add child node, check index sets for consistency. */
73 symmetry &add(const symmetry &c);
75 /** Verify that all indices of this node are in the range [0..n-1].
76 * This function throws an exception if the verification fails.
77 * If the top node has a type != none and no children, add all indices
78 * in the range [0..n-1] as children. */
79 void validate(unsigned n);
81 /** Check whether this node actually represents any kind of symmetry. */
82 bool has_symmetry() const {return type != none || !children.empty(); }
85 void do_print(const print_context & c, unsigned level) const;
86 void do_print_tree(const print_tree & c, unsigned level) const;
87 unsigned calchash() const;
91 /** Type of symmetry described by this node. */
94 /** Sorted union set of all indices handled by this node. */
95 std::set<unsigned> indices;
97 /** Vector of child nodes. */
104 inline symmetry sy_none() { return symmetry(); }
105 inline symmetry sy_none(const symmetry &c1, const symmetry &c2) { return symmetry(symmetry::none, c1, c2); }
106 inline symmetry sy_none(const symmetry &c1, const symmetry &c2, const symmetry &c3) { return symmetry(symmetry::none, c1, c2).add(c3); }
107 inline symmetry sy_none(const symmetry &c1, const symmetry &c2, const symmetry &c3, const symmetry &c4) { return symmetry(symmetry::none, c1, c2).add(c3).add(c4); }
109 inline symmetry sy_symm() { symmetry s; s.set_type(symmetry::symmetric); return s; }
110 inline symmetry sy_symm(const symmetry &c1, const symmetry &c2) { return symmetry(symmetry::symmetric, c1, c2); }
111 inline symmetry sy_symm(const symmetry &c1, const symmetry &c2, const symmetry &c3) { return symmetry(symmetry::symmetric, c1, c2).add(c3); }
112 inline symmetry sy_symm(const symmetry &c1, const symmetry &c2, const symmetry &c3, const symmetry &c4) { return symmetry(symmetry::symmetric, c1, c2).add(c3).add(c4); }
114 inline symmetry sy_anti() { symmetry s; s.set_type(symmetry::antisymmetric); return s; }
115 inline symmetry sy_anti(const symmetry &c1, const symmetry &c2) { return symmetry(symmetry::antisymmetric, c1, c2); }
116 inline symmetry sy_anti(const symmetry &c1, const symmetry &c2, const symmetry &c3) { return symmetry(symmetry::antisymmetric, c1, c2).add(c3); }
117 inline symmetry sy_anti(const symmetry &c1, const symmetry &c2, const symmetry &c3, const symmetry &c4) { return symmetry(symmetry::antisymmetric, c1, c2).add(c3).add(c4); }
119 inline symmetry sy_cycl() { symmetry s; s.set_type(symmetry::cyclic); return s; }
120 inline symmetry sy_cycl(const symmetry &c1, const symmetry &c2) { return symmetry(symmetry::cyclic, c1, c2); }
121 inline symmetry sy_cycl(const symmetry &c1, const symmetry &c2, const symmetry &c3) { return symmetry(symmetry::cyclic, c1, c2).add(c3); }
122 inline symmetry sy_cycl(const symmetry &c1, const symmetry &c2, const symmetry &c3, const symmetry &c4) { return symmetry(symmetry::cyclic, c1, c2).add(c3).add(c4); }
124 // These return references to preallocated common symmetries (similar to
125 // the numeric flyweights).
126 const symmetry & not_symmetric();
127 const symmetry & symmetric2();
128 const symmetry & symmetric3();
129 const symmetry & symmetric4();
130 const symmetry & antisymmetric2();
131 const symmetry & antisymmetric3();
132 const symmetry & antisymmetric4();
134 /** Canonicalize the order of elements of an expression vector, according to
135 * the symmetry properties defined in a symmetry tree.
137 * @param v Start of expression vector
138 * @param symm Root node of symmetry tree
139 * @return the overall sign introduced by the reordering (+1, -1 or 0)
140 * or INT_MAX if nothing changed */
141 extern int canonicalize(exvector::iterator v, const symmetry &symm);
143 /** Symmetrize expression over a set of objects (symbols, indices). */
144 ex symmetrize(const ex & e, exvector::const_iterator first, exvector::const_iterator last);
146 /** Symmetrize expression over a set of objects (symbols, indices). */
147 inline ex symmetrize(const ex & e, const exvector & v)
149 return symmetrize(e, v.begin(), v.end());
152 /** Antisymmetrize expression over a set of objects (symbols, indices). */
153 ex antisymmetrize(const ex & e, exvector::const_iterator first, exvector::const_iterator last);
155 /** Antisymmetrize expression over a set of objects (symbols, indices). */
156 inline ex antisymmetrize(const ex & e, const exvector & v)
158 return antisymmetrize(e, v.begin(), v.end());
161 /** Symmetrize expression by cyclic permuation over a set of objects
162 * (symbols, indices). */
163 ex symmetrize_cyclic(const ex & e, exvector::const_iterator first, exvector::const_iterator last);
165 /** Symmetrize expression by cyclic permutation over a set of objects
166 * (symbols, indices). */
167 inline ex symmetrize_cyclic(const ex & e, const exvector & v)
169 return symmetrize(e, v.begin(), v.end());
174 #endif // ndef __GINAC_SYMMETRY_H__