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/** @file idx.h
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*
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* Interface to GiNaC's indices. */
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/*
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* GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#ifndef __GINAC_IDX_H__
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#define __GINAC_IDX_H__
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#include "ex.h"
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namespace GiNaC {
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/** This class holds one index of an indexed object. Indices can
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* theoretically consist of any symbolic expression but they are usually
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* only just a symbol (e.g. "mu", "i") or numeric (integer). Indices belong
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* to a space with a certain numeric or symbolic dimension. */
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class idx : public basic
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{
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GINAC_DECLARE_REGISTERED_CLASS(idx, basic)
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// other constructors
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public:
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/** Construct index with given value and dimension.
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*
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* @param v Value of index (numeric or symbolic)
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* @param dim Dimension of index space (numeric or symbolic)
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* @return newly constructed index */
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explicit idx(const ex & v, const ex & dim);
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// functions overriding virtual functions from bases classes
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public:
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void printraw(std::ostream & os) const;
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void printtree(std::ostream & os, unsigned indent) const;
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void print(std::ostream & os, unsigned upper_precedence=0) const;
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bool info(unsigned inf) const;
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protected:
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ex subs(const lst & ls, const lst & lr) const;
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// new virtual functions in this class
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public:
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/** Check whether the index forms a dummy index pair with another index
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* of the same type. */
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virtual bool is_dummy_pair_same_type(const basic & other) const;
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// non-virtual functions in this class
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public:
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/** Get value of index. */
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ex get_value(void) const {return value;}
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/** Check whether the index is numeric. */
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bool is_numeric(void) const {return is_ex_exactly_of_type(value, numeric);}
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/** Check whether the index is symbolic. */
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bool is_symbolic(void) const {return !is_ex_exactly_of_type(value, numeric);}
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/** Get dimension of index space. */
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ex get_dim(void) const {return dim;}
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/** Check whether the dimension is numeric. */
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bool is_dim_numeric(void) const {return is_ex_exactly_of_type(dim, numeric);}
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/** Check whether the dimension is symbolic. */
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bool is_dim_symbolic(void) const {return !is_ex_exactly_of_type(dim, numeric);}
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// member variables
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protected:
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ex value; /**< Expression that constitutes the index (numeric or symbolic name) */
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ex dim; /**< Dimension of space (can be symbolic or numeric) */
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};
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/** This class holds an index with a variance (co- or contravariant). There
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* is an associated metric tensor that can be used to raise/lower indices. */
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class varidx : public idx
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{
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GINAC_DECLARE_REGISTERED_CLASS(varidx, idx)
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// other constructors
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public:
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/** Construct index with given value, dimension and variance.
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*
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* @param v Value of index (numeric or symbolic)
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* @param dim Dimension of index space (numeric or symbolic)
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* @param covariant Make covariant index (default is contravariant)
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* @return newly constructed index */
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varidx(const ex & v, const ex & dim, bool covariant = false);
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// functions overriding virtual functions from bases classes
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public:
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void print(std::ostream & os, unsigned upper_precedence=0) const;
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bool is_dummy_pair_same_type(const basic & other) const;
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// non-virtual functions in this class
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public:
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/** Check whether the index is covariant. */
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bool is_covariant(void) const {return covariant;}
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/** Check whether the index is contravariant (not covariant). */
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bool is_contravariant(void) const {return !covariant;}
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/** Make a new index with the same value but the opposite variance. */
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ex toggle_variance(void) const;
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// member variables
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protected:
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bool covariant; /**< x.mu, default is contravariant: x~mu */
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};
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// utility functions
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inline const idx &ex_to_idx(const ex & e)
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{
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return static_cast<const idx &>(*e.bp);
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}
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inline const varidx &ex_to_varidx(const ex & e)
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{
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return static_cast<const varidx &>(*e.bp);
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}
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/** Check whether two indices form a dummy pair. */
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bool is_dummy_pair(const idx & i1, const idx & i2);
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/** Check whether two expressions form a dummy index pair. */
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bool is_dummy_pair(const ex & e1, const ex & e2);
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} // namespace GiNaC
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#endif // ndef __GINAC_IDX_H__
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