X-Git-Url: https://ginac.de/ginac.git//ginac.git?a=blobdiff_plain;f=ginac%2Findexed.cpp;h=b3c18ba51989ba37bdebb03b111f007858721ec1;hb=f69a24a4fd6caf42ef773d1cef21562a8afa068a;hp=b8b70f7e9d5ae853649c85c709fb895182aaf91d;hpb=3ac17e18ada69428fe170c10abcc5f33a30f0676;p=ginac.git

diff --git a/ginac/indexed.cpp b/ginac/indexed.cpp
index b8b70f7e..b3c18ba5 100644
--- a/ginac/indexed.cpp
+++ b/ginac/indexed.cpp
@@ -3,7 +3,7 @@
  *  Implementation of GiNaC's indexed expressions. */
 
 /*
- *  GiNaC Copyright (C) 1999-2006 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2007 Johannes Gutenberg University Mainz, Germany
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
@@ -23,6 +23,7 @@
 #include <iostream>
 #include <sstream>
 #include <stdexcept>
+#include <limits>
 
 #include "indexed.h"
 #include "idx.h"
@@ -39,6 +40,7 @@
 #include "utils.h"
 #include "integral.h"
 #include "matrix.h"
+#include "inifcns.h"
 
 namespace GiNaC {
 
@@ -305,7 +307,7 @@ ex indexed::eval(int level) const
 		exvector v = seq;
 		GINAC_ASSERT(is_exactly_a<symmetry>(symtree));
 		int sig = canonicalize(v.begin() + 1, ex_to<symmetry>(symtree));
-		if (sig != INT_MAX) {
+		if (sig != std::numeric_limits<int>::max()) {
 			// Something has changed while sorting indices, more evaluations later
 			if (sig == 0)
 				return _ex0;
@@ -317,6 +319,20 @@ ex indexed::eval(int level) const
 	return ex_to<basic>(base).eval_indexed(*this);
 }
 
+ex indexed::real_part() const
+{
+	if(op(0).info(info_flags::real))
+		return *this;
+	return real_part_function(*this).hold();
+}
+
+ex indexed::imag_part() const
+{
+	if(op(0).info(info_flags::real))
+		return 0;
+	return imag_part_function(*this).hold();
+}
+
 ex indexed::thiscontainer(const exvector & v) const
 {
 	return indexed(ex_to<symmetry>(symtree), v);
@@ -624,10 +640,60 @@ bool reposition_dummy_indices(ex & e, exvector & variant_dummy_indices, exvector
 {
 	bool something_changed = false;
 
+	// Find dummy symbols that occur twice in the same indexed object.
+	exvector local_var_dummies;
+	local_var_dummies.reserve(e.nops()/2);
+	for (size_t i=1; i<e.nops(); ++i) {
+		if (!is_a<varidx>(e.op(i)))
+			continue;
+		for (size_t j=i+1; j<e.nops(); ++j) {
+			if (is_dummy_pair(e.op(i), e.op(j))) {
+				local_var_dummies.push_back(e.op(i));
+				for (exvector::iterator k = variant_dummy_indices.begin();
+						k!=variant_dummy_indices.end(); ++k) {
+					if (e.op(i).op(0) == k->op(0)) {
+						variant_dummy_indices.erase(k);
+						break;
+					}
+				}
+				break;
+			}
+		}
+	}
+
+	// In the case where a dummy symbol occurs twice in the same indexed object
+	// we try all posibilities of raising/lowering and keep the least one in
+	// the sense of ex_is_less.
+	ex optimal_e = e;
+	size_t numpossibs = 1 << local_var_dummies.size();
+	for (size_t i=0; i<numpossibs; ++i) {
+		ex try_e = e;
+		for (size_t j=0; j<local_var_dummies.size(); ++j) {
+			exmap m;
+			if (1<<j & i) {
+				ex curr_idx = local_var_dummies[j];
+				ex curr_toggle = ex_to<varidx>(curr_idx).toggle_variance();
+				m[curr_idx] = curr_toggle;
+				m[curr_toggle] = curr_idx;
+			}
+			try_e = e.subs(m, subs_options::no_pattern);
+		}
+		if(ex_is_less()(try_e, optimal_e))
+		{	optimal_e = try_e;
+			something_changed = true;
+		}
+	}
+	e = optimal_e;
+
+	if (!is_a<indexed>(e))
+		return true;
+
+	exvector seq = ex_to<indexed>(e).seq;
+
 	// If a dummy index is encountered for the first time in the
 	// product, pull it up, otherwise, pull it down
-	exvector::const_iterator it2, it2start, it2end;
-	for (it2start = ex_to<indexed>(e).seq.begin(), it2end = ex_to<indexed>(e).seq.end(), it2 = it2start + 1; it2 != it2end; ++it2) {
+	for (exvector::iterator it2 = seq.begin()+1, it2end = seq.end();
+			it2 != it2end; ++it2) {
 		if (!is_exactly_a<varidx>(*it2))
 			continue;
 
@@ -635,14 +701,20 @@ bool reposition_dummy_indices(ex & e, exvector & variant_dummy_indices, exvector
 		for (vit = variant_dummy_indices.begin(), vitend = variant_dummy_indices.end(); vit != vitend; ++vit) {
 			if (it2->op(0).is_equal(vit->op(0))) {
 				if (ex_to<varidx>(*it2).is_covariant()) {
-					e = e.subs(lst(
-						*it2 == ex_to<varidx>(*it2).toggle_variance(),
-						ex_to<varidx>(*it2).toggle_variance() == *it2
-					), subs_options::no_pattern);
+					/*
+					 * N.B. we don't want to use
+					 *
+					 *  e = e.subs(lst(
+					 *  *it2 == ex_to<varidx>(*it2).toggle_variance(),
+					 *  ex_to<varidx>(*it2).toggle_variance() == *it2
+					 *  ), subs_options::no_pattern);
+					 *
+					 * since this can trigger non-trivial repositioning of indices,
+					 * e.g. due to non-trivial symmetry properties of e, thus
+					 * invalidating iterators
+					 */
+					*it2 = ex_to<varidx>(*it2).toggle_variance();
 					something_changed = true;
-					it2 = ex_to<indexed>(e).seq.begin() + (it2 - it2start);
-					it2start = ex_to<indexed>(e).seq.begin();
-					it2end = ex_to<indexed>(e).seq.end();
 				}
 				moved_indices.push_back(*vit);
 				variant_dummy_indices.erase(vit);
@@ -653,11 +725,8 @@ bool reposition_dummy_indices(ex & e, exvector & variant_dummy_indices, exvector
 		for (vit = moved_indices.begin(), vitend = moved_indices.end(); vit != vitend; ++vit) {
 			if (it2->op(0).is_equal(vit->op(0))) {
 				if (ex_to<varidx>(*it2).is_contravariant()) {
-					e = e.subs(*it2 == ex_to<varidx>(*it2).toggle_variance(), subs_options::no_pattern);
+					*it2 = ex_to<varidx>(*it2).toggle_variance();
 					something_changed = true;
-					it2 = ex_to<indexed>(e).seq.begin() + (it2 - it2start);
-					it2start = ex_to<indexed>(e).seq.begin();
-					it2end = ex_to<indexed>(e).seq.end();
 				}
 				goto next_index;
 			}
@@ -666,6 +735,9 @@ bool reposition_dummy_indices(ex & e, exvector & variant_dummy_indices, exvector
 next_index: ;
 	}
 
+	if (something_changed)
+		e = ex_to<indexed>(e).thiscontainer(seq);
+
 	return something_changed;
 }
 
@@ -1486,44 +1558,33 @@ ex expand_dummy_sum(const ex & e, bool subs_idx)
 	pointer_to_map_function_1arg<bool> fcn(expand_dummy_sum, subs_idx);
 	if (is_a<add>(e_expanded) || is_a<lst>(e_expanded) || is_a<matrix>(e_expanded)) {
 		return e_expanded.map(fcn);
-	} else if (is_a<ncmul>(e_expanded) || is_a<mul>(e_expanded) || is_a<power>(e_expanded)) {
-		exvector v = get_all_dummy_indices(e_expanded);
-		exvector::const_iterator it = v.begin(), itend = v.end();
-		while (it != itend) {
-			varidx nu = ex_to<varidx>(*it);
-			if (nu.is_dim_numeric()) {
-				ex en = 0;
-				for (int i=0; i < ex_to<numeric>(nu.get_dim()).to_int(); i++) {
-					if (is_a<varidx>(nu) && !subs_idx) {
-						en += e_expanded.subs(lst(nu == varidx(i, nu.get_dim(), true), nu.toggle_variance() == varidx(i, nu.get_dim())));
-					} else {
-						en += e_expanded.subs(lst(nu == idx(i, nu.get_dim()), nu.toggle_variance() == idx(i, nu.get_dim())));
-					}
-				}
-				return expand_dummy_sum(en, subs_idx);
-			} 
-			++it;
-		}
-		return e;
-	} else if (is_a<indexed>(e_expanded)) {
-		exvector v = ex_to<indexed>(e_expanded).get_dummy_indices();
-		exvector::const_iterator it = v.begin(), itend = v.end();
-		while (it != itend) {
-			varidx nu = ex_to<varidx>(*it);
-			if (nu.is_dim_numeric()) {
+	} else if (is_a<ncmul>(e_expanded) || is_a<mul>(e_expanded) || is_a<power>(e_expanded) || is_a<indexed>(e_expanded)) {
+		exvector v;
+		if (is_a<indexed>(e_expanded))
+			v = ex_to<indexed>(e_expanded).get_dummy_indices();
+		else
+			v = get_all_dummy_indices(e_expanded);
+		ex result = e_expanded;
+		for(exvector::const_iterator it=v.begin(); it!=v.end(); ++it) {
+			ex nu = *it;
+			if (ex_to<idx>(nu).get_dim().info(info_flags::nonnegint)) {
+				int idim = ex_to<numeric>(ex_to<idx>(nu).get_dim()).to_int();
 				ex en = 0;
-				for (int i=0; i < ex_to<numeric>(nu.get_dim()).to_int(); i++) {
-					if (is_a<varidx>(nu) && !subs_idx) {
-						en += e_expanded.subs(lst(nu == varidx(i, nu.get_dim(), true), nu.toggle_variance() == varidx(i, nu.get_dim())));
+				for (int i=0; i < idim; i++) {
+					if (subs_idx && is_a<varidx>(nu)) {
+						ex other = ex_to<varidx>(nu).toggle_variance();
+						en += result.subs(lst(
+							nu == idx(i, idim),
+							other == idx(i, idim)
+						));
 					} else {
-						en += e_expanded.subs(lst(nu == idx(i, nu.get_dim()), nu.toggle_variance() == idx(i, nu.get_dim())));
+						en += result.subs( nu.op(0) == i );
 					}
 				}
-				return expand_dummy_sum(en, subs_idx);
-			} 
-			++it;
+				result = en;
+			}
 		}
-		return e;
+		return result;
 	} else {
 		return e;
 	}