X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Ftensor.cpp;h=0c36a68002423d712f4d8afa5ec903716ffba7e7;hp=8881425f6e4c2189dc73ed2132e1f82bd34299cc;hb=b8b8cfbb72bfa59b01371f67f542914cf55f2ab9;hpb=d448856f20cb58f939ddbf636e7f72e3599b1468

diff --git a/ginac/tensor.cpp b/ginac/tensor.cpp
index 8881425f..0c36a680 100644
--- a/ginac/tensor.cpp
+++ b/ginac/tensor.cpp
@@ -3,7 +3,7 @@
  *  Implementation of GiNaC's special tensors. */
 
 /*
- *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2002 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
@@ -20,6 +20,7 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <iostream>
 #include <stdexcept>
 #include <vector>
 
@@ -34,7 +35,6 @@
 #include "print.h"
 #include "archive.h"
 #include "utils.h"
-#include "debugmsg.h"
 
 namespace GiNaC {
 
@@ -46,14 +46,9 @@ GINAC_IMPLEMENT_REGISTERED_CLASS(spinmetric, tensmetric)
 GINAC_IMPLEMENT_REGISTERED_CLASS(tensepsilon, tensor)
 
 //////////
-// default constructor, destructor, copy constructor assignment operator and helpers
+// default ctor, dtor, copy ctor, assignment operator and helpers
 //////////
 
-tensor::tensor(unsigned ti) : inherited(ti)
-{
-	debugmsg("tensor constructor from unsigned", LOGLEVEL_CONSTRUCT); \
-}
-
 DEFAULT_CTORS(tensor)
 DEFAULT_CTORS(tensdelta)
 DEFAULT_CTORS(tensmetric)
@@ -64,19 +59,16 @@ DEFAULT_DESTROY(tensepsilon)
 
 minkmetric::minkmetric() : pos_sig(false)
 {
-	debugmsg("minkmetric default constructor", LOGLEVEL_CONSTRUCT);
 	tinfo_key = TINFO_minkmetric;
 }
 
 spinmetric::spinmetric()
 {
-	debugmsg("spinmetric default constructor", LOGLEVEL_CONSTRUCT);
 	tinfo_key = TINFO_spinmetric;
 }
 
 minkmetric::minkmetric(bool ps) : pos_sig(ps)
 {
-	debugmsg("minkmetric constructor from bool", LOGLEVEL_CONSTRUCT);
 	tinfo_key = TINFO_minkmetric;
 }
 
@@ -88,13 +80,11 @@ void minkmetric::copy(const minkmetric & other)
 
 tensepsilon::tensepsilon() : minkowski(false), pos_sig(false)
 {
-	debugmsg("tensepsilon default constructor", LOGLEVEL_CONSTRUCT);
 	tinfo_key = TINFO_tensepsilon;
 }
 
 tensepsilon::tensepsilon(bool mink, bool ps) : minkowski(mink), pos_sig(ps)
 {
-	debugmsg("tensepsilon constructor from bool,bool", LOGLEVEL_CONSTRUCT);
 	tinfo_key = TINFO_tensepsilon;
 }
 
@@ -118,7 +108,6 @@ DEFAULT_UNARCHIVE(tensepsilon)
 
 minkmetric::minkmetric(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
 {
-	debugmsg("minkmetric constructor from archive_node", LOGLEVEL_CONSTRUCT);
 	n.find_bool("pos_sig", pos_sig);
 }
 
@@ -130,7 +119,6 @@ void minkmetric::archive(archive_node &n) const
 
 tensepsilon::tensepsilon(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
 {
-	debugmsg("tensepsilon constructor from archive_node", LOGLEVEL_CONSTRUCT);
 	n.find_bool("minkowski", minkowski);
 	n.find_bool("pos_sig", pos_sig);
 }
@@ -191,17 +179,22 @@ ex tensdelta::eval_indexed(const basic & i) const
 	const idx & i1 = ex_to<idx>(i.op(1));
 	const idx & i2 = ex_to<idx>(i.op(2));
 
-	// Trace of delta tensor is the dimension of the space
-	if (is_dummy_pair(i1, i2))
-		return i1.get_dim();
+	// Trace of delta tensor is the (effective) dimension of the space
+	if (is_dummy_pair(i1, i2)) {
+		try {
+			return i1.minimal_dim(i2);
+		} catch (std::exception &e) {
+			return i.hold();
+		}
+	}
 
 	// Numeric evaluation
 	if (static_cast<const indexed &>(i).all_index_values_are(info_flags::integer)) {
 		int n1 = ex_to<numeric>(i1.get_value()).to_int(), n2 = ex_to<numeric>(i2.get_value()).to_int();
 		if (n1 == n2)
-			return _ex1();
+			return _ex1;
 		else
-			return _ex0();
+			return _ex0;
 	}
 
 	// No further simplifications
@@ -220,6 +213,13 @@ ex tensmetric::eval_indexed(const basic & i) const
 	const varidx & i1 = ex_to<varidx>(i.op(1));
 	const varidx & i2 = ex_to<varidx>(i.op(2));
 
+	// The dimension of the indices must be equal, otherwise we use the minimal
+	// dimension
+	if (!i1.get_dim().is_equal(i2.get_dim())) {
+		ex min_dim = i1.minimal_dim(i2);
+		return i.subs(lst(i1 == i1.replace_dim(min_dim), i2 == i2.replace_dim(min_dim)));
+	}
+
 	// A metric tensor with one covariant and one contravariant index gets
 	// replaced by a delta tensor
 	if (i1.is_covariant() != i2.is_covariant())
@@ -245,11 +245,11 @@ ex minkmetric::eval_indexed(const basic & i) const
 	if (static_cast<const indexed &>(i).all_index_values_are(info_flags::nonnegint)) {
 		int n1 = ex_to<numeric>(i1.get_value()).to_int(), n2 = ex_to<numeric>(i2.get_value()).to_int();
 		if (n1 != n2)
-			return _ex0();
+			return _ex0;
 		else if (n1 == 0)
-			return pos_sig ? _ex_1() : _ex1();
+			return pos_sig ? _ex_1 : _ex1;
 		else
-			return pos_sig ? _ex1() : _ex_1();
+			return pos_sig ? _ex1 : _ex_1;
 	}
 
 	// Perform the usual evaluations of a metric tensor
@@ -270,17 +270,17 @@ ex spinmetric::eval_indexed(const basic & i) const
 
 	// Convolutions are zero
 	if (!(static_cast<const indexed &>(i).get_dummy_indices().empty()))
-		return _ex0();
+		return _ex0;
 
 	// Numeric evaluation
 	if (static_cast<const indexed &>(i).all_index_values_are(info_flags::nonnegint)) {
 		int n1 = ex_to<numeric>(i1.get_value()).to_int(), n2 = ex_to<numeric>(i2.get_value()).to_int();
 		if (n1 == n2)
-			return _ex0();
+			return _ex0;
 		else if (n1 < n2)
-			return _ex1();
+			return _ex1;
 		else
-			return _ex_1();
+			return _ex_1;
 	}
 
 	// No further simplifications
@@ -296,7 +296,7 @@ ex tensepsilon::eval_indexed(const basic & i) const
 
 	// Convolutions are zero
 	if (!(static_cast<const indexed &>(i).get_dummy_indices().empty()))
-		return _ex0();
+		return _ex0;
 
 	// Numeric evaluation
 	if (static_cast<const indexed &>(i).all_index_values_are(info_flags::nonnegint)) {
@@ -330,15 +330,9 @@ ex tensepsilon::eval_indexed(const basic & i) const
 	return i.hold();
 }
 
-/** Contraction of an indexed delta tensor with something else. */
-bool tensdelta::contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const
+bool tensor::replace_contr_index(exvector::iterator self, exvector::iterator other) const
 {
-	GINAC_ASSERT(is_a<indexed>(*self));
-	GINAC_ASSERT(is_a<indexed>(*other));
-	GINAC_ASSERT(self->nops() == 3);
-	GINAC_ASSERT(is_a<tensdelta>(self->op(0)));
-
-	// Try to contract first index
+	// Try to contract the first index
 	const idx *self_idx = &ex_to<idx>(self->op(1));
 	const idx *free_idx = &ex_to<idx>(self->op(2));
 	bool first_index_tried = false;
@@ -349,18 +343,24 @@ again:
 			const idx &other_idx = ex_to<idx>(other->op(i));
 			if (is_dummy_pair(*self_idx, other_idx)) {
 
-				// Contraction found, remove delta tensor and substitute
-				// index in second object
-				*self = _ex1();
-				*other = other->subs(other_idx == *free_idx);
-				return true;
+				// Contraction found, remove this tensor and substitute the
+				// index in the second object
+				try {
+					// minimal_dim() throws an exception when index dimensions are not comparable
+					ex min_dim = self_idx->minimal_dim(other_idx);
+					*self = _ex1;
+					*other = other->subs(other_idx == free_idx->replace_dim(min_dim));
+					return true;
+				} catch (std::exception &e) {
+					return false;
+				}
 			}
 		}
 	}
 
 	if (!first_index_tried) {
 
-		// No contraction with first index found, try second index
+		// No contraction with the first index found, try the second index
 		self_idx = &ex_to<idx>(self->op(2));
 		free_idx = &ex_to<idx>(self->op(1));
 		first_index_tried = true;
@@ -370,6 +370,19 @@ again:
 	return false;
 }
 
+/** Contraction of an indexed delta tensor with something else. */
+bool tensdelta::contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const
+{
+	GINAC_ASSERT(is_a<indexed>(*self));
+	GINAC_ASSERT(is_a<indexed>(*other));
+	GINAC_ASSERT(self->nops() == 3);
+	GINAC_ASSERT(is_a<tensdelta>(self->op(0)));
+
+	// Replace the dummy index with this tensor's other index and remove
+	// the tensor (this is valid for contractions with all other tensors)
+	return replace_contr_index(self, other);
+}
+
 /** Contraction of an indexed metric tensor with something else. */
 bool tensmetric::contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const
 {
@@ -383,36 +396,9 @@ bool tensmetric::contract_with(exvector::iterator self, exvector::iterator other
 	if (is_ex_of_type(other->op(0), tensdelta))
 		return false;
 
-	// Try to contract first index
-	const idx *self_idx = &ex_to<idx>(self->op(1));
-	const idx *free_idx = &ex_to<idx>(self->op(2));
-	bool first_index_tried = false;
-
-again:
-	if (self_idx->is_symbolic()) {
-		for (unsigned i=1; i<other->nops(); i++) {
-			const idx &other_idx = ex_to<idx>(other->op(i));
-			if (is_dummy_pair(*self_idx, other_idx)) {
-
-				// Contraction found, remove metric tensor and substitute
-				// index in second object
-				*self = _ex1();
-				*other = other->subs(other_idx == *free_idx);
-				return true;
-			}
-		}
-	}
-
-	if (!first_index_tried) {
-
-		// No contraction with first index found, try second index
-		self_idx = &ex_to<idx>(self->op(2));
-		free_idx = &ex_to<idx>(self->op(1));
-		first_index_tried = true;
-		goto again;
-	}
-
-	return false;
+	// Replace the dummy index with this tensor's other index and remove
+	// the tensor (this is valid for contractions with all other tensors)
+	return replace_contr_index(self, other);
 }
 
 /** Contraction of an indexed spinor metric with something else. */
@@ -432,25 +418,25 @@ bool spinmetric::contract_with(exvector::iterator self, exvector::iterator other
 
 		if (is_dummy_pair(self_i1, other_i1)) {
 			if (is_dummy_pair(self_i2, other_i2))
-				*self = _ex2();
+				*self = _ex2;
 			else
 				*self = delta_tensor(self_i2, other_i2);
-			*other = _ex1();
+			*other = _ex1;
 			return true;
 		} else if (is_dummy_pair(self_i1, other_i2)) {
 			if (is_dummy_pair(self_i2, other_i1))
-				*self = _ex_2();
+				*self = _ex_2;
 			else
 				*self = -delta_tensor(self_i2, other_i1);
-			*other = _ex1();
+			*other = _ex1;
 			return true;
 		} else if (is_dummy_pair(self_i2, other_i1)) {
 			*self = -delta_tensor(self_i1, other_i2);
-			*other = _ex1();
+			*other = _ex1;
 			return true;
 		} else if (is_dummy_pair(self_i2, other_i2)) {
 			*self = delta_tensor(self_i1, other_i1);
-			*other = _ex1();
+			*other = _ex1;
 			return true;
 		}
 	}
@@ -517,46 +503,8 @@ bool tensepsilon::contract_with(exvector::iterator self, exvector::iterator othe
 		}
 		int sign = minkowski ? -1 : 1;
 		*self = sign * M.determinant().simplify_indexed();
-		*other = _ex1();
+		*other = _ex1;
 		return true;
-
-	} else if (other->return_type() == return_types::commutative) {
-
-#if 0
-		// This handles eps.i.j.k * p.j * p.k = 0
-		// Maybe something like this should go to simplify_indexed() because
-		// such relations are true for any antisymmetric tensors...
-		exvector c;
-
-		// Handle all indices of the epsilon tensor
-		for (int i=0; i<num; i++) {
-			ex idx = self->op(i+1);
-
-			// Look whether there's a contraction with this index
-			exvector::const_iterator ait, aitend = v.end();
-			for (ait = v.begin(); ait != aitend; ait++) {
-				if (ait == self)
-					continue;
-				if (is_a<indexed>(*ait) && ait->return_type() == return_types::commutative && ex_to<indexed>(*ait).has_dummy_index_for(idx) && ait->nops() == 2) {
-
-					// Yes, did we already have another contraction with the same base expression?
-					ex base = ait->op(0);
-					if (std::find_if(c.begin(), c.end(), bind2nd(ex_is_equal(), base)) == c.end()) {
-
-						// No, add the base expression to the list
-						c.push_back(base);
-
-					} else {
-
-						// Yes, the contraction is zero
-						*self = _ex0();
-						*other = _ex0();
-						return true;
-					}
-				}
-			}
-		}
-#endif
 	}
 
 	return false;
@@ -608,7 +556,7 @@ ex epsilon_tensor(const ex & i1, const ex & i2)
 	ex dim = ex_to<idx>(i1).get_dim();
 	if (!dim.is_equal(ex_to<idx>(i2).get_dim()))
 		throw(std::invalid_argument("all indices of epsilon tensor must have the same dimension"));
-	if (!ex_to<idx>(i1).get_dim().is_equal(_ex2()))
+	if (!ex_to<idx>(i1).get_dim().is_equal(_ex2))
 		throw(std::runtime_error("index dimension of epsilon tensor must match number of indices"));
 
 	return indexed(tensepsilon(), sy_anti(), i1, i2);
@@ -622,7 +570,7 @@ ex epsilon_tensor(const ex & i1, const ex & i2, const ex & i3)
 	ex dim = ex_to<idx>(i1).get_dim();
 	if (!dim.is_equal(ex_to<idx>(i2).get_dim()) || !dim.is_equal(ex_to<idx>(i3).get_dim()))
 		throw(std::invalid_argument("all indices of epsilon tensor must have the same dimension"));
-	if (!ex_to<idx>(i1).get_dim().is_equal(_ex3()))
+	if (!ex_to<idx>(i1).get_dim().is_equal(_ex3))
 		throw(std::runtime_error("index dimension of epsilon tensor must match number of indices"));
 
 	return indexed(tensepsilon(), sy_anti(), i1, i2, i3);
@@ -636,22 +584,10 @@ ex lorentz_eps(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool
 	ex dim = ex_to<idx>(i1).get_dim();
 	if (!dim.is_equal(ex_to<idx>(i2).get_dim()) || !dim.is_equal(ex_to<idx>(i3).get_dim()) || !dim.is_equal(ex_to<idx>(i4).get_dim()))
 		throw(std::invalid_argument("all indices of epsilon tensor must have the same dimension"));
-	if (!ex_to<idx>(i1).get_dim().is_equal(_ex4()))
+	if (!ex_to<idx>(i1).get_dim().is_equal(_ex4))
 		throw(std::runtime_error("index dimension of epsilon tensor must match number of indices"));
 
 	return indexed(tensepsilon(true, pos_sig), sy_anti(), i1, i2, i3, i4);
 }
 
-ex eps0123(const ex & i1, const ex & i2, const ex & i3, const ex & i4, bool pos_sig)
-{
-	if (!is_ex_of_type(i1, varidx) || !is_ex_of_type(i2, varidx) || !is_ex_of_type(i3, varidx) || !is_ex_of_type(i4, varidx))
-		throw(std::invalid_argument("indices of epsilon tensor must be of type varidx"));
-
-	ex dim = ex_to<idx>(i1).get_dim();
-	if (dim.is_equal(4))
-		return lorentz_eps(i1, i2, i3, i4, pos_sig);
-	else
-		return indexed(tensepsilon(true, pos_sig), sy_anti(), i1, i2, i3, i4);
-}
-
 } // namespace GiNaC