* Implementation of GiNaC's special tensors. */
/*
- * GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2003 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
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
+#include <iostream>
#include <stdexcept>
#include <vector>
#include "relational.h"
#include "lst.h"
#include "numeric.h"
+#include "matrix.h"
#include "print.h"
#include "archive.h"
#include "utils.h"
-#include "debugmsg.h"
namespace GiNaC {
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)
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;
}
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;
}
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);
}
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);
}
}
//////////
-// functions overriding virtual functions from bases classes
+// functions overriding virtual functions from base classes
//////////
DEFAULT_COMPARE(tensor)
int minkmetric::compare_same_type(const basic & other) const
{
- GINAC_ASSERT(is_of_type(other, minkmetric));
+ GINAC_ASSERT(is_a<minkmetric>(other));
const minkmetric &o = static_cast<const minkmetric &>(other);
if (pos_sig != o.pos_sig)
int tensepsilon::compare_same_type(const basic & other) const
{
- GINAC_ASSERT(is_of_type(other, tensepsilon));
+ GINAC_ASSERT(is_a<tensepsilon>(other));
const tensepsilon &o = static_cast<const tensepsilon &>(other);
if (minkowski != o.minkowski)
/** Automatic symbolic evaluation of an indexed delta tensor. */
ex tensdelta::eval_indexed(const basic & i) const
{
- GINAC_ASSERT(is_of_type(i, indexed));
+ GINAC_ASSERT(is_a<indexed>(i));
GINAC_ASSERT(i.nops() == 3);
- GINAC_ASSERT(is_ex_of_type(i.op(0), tensdelta));
+ GINAC_ASSERT(is_a<tensdelta>(i.op(0)));
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();
+ // 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)));
+ }
+
+ // 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
/** Automatic symbolic evaluation of an indexed metric tensor. */
ex tensmetric::eval_indexed(const basic & i) const
{
- GINAC_ASSERT(is_of_type(i, indexed));
+ GINAC_ASSERT(is_a<indexed>(i));
GINAC_ASSERT(i.nops() == 3);
- GINAC_ASSERT(is_ex_of_type(i.op(0), tensmetric));
- GINAC_ASSERT(is_ex_of_type(i.op(1), varidx));
- GINAC_ASSERT(is_ex_of_type(i.op(2), varidx));
+ GINAC_ASSERT(is_a<tensmetric>(i.op(0)));
+ GINAC_ASSERT(is_a<varidx>(i.op(1)));
+ GINAC_ASSERT(is_a<varidx>(i.op(2)));
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())
/** Automatic symbolic evaluation of an indexed Lorentz metric tensor. */
ex minkmetric::eval_indexed(const basic & i) const
{
- GINAC_ASSERT(is_of_type(i, indexed));
+ GINAC_ASSERT(is_a<indexed>(i));
GINAC_ASSERT(i.nops() == 3);
- GINAC_ASSERT(is_ex_of_type(i.op(0), minkmetric));
- GINAC_ASSERT(is_ex_of_type(i.op(1), varidx));
- GINAC_ASSERT(is_ex_of_type(i.op(2), varidx));
+ GINAC_ASSERT(is_a<minkmetric>(i.op(0)));
+ GINAC_ASSERT(is_a<varidx>(i.op(1)));
+ GINAC_ASSERT(is_a<varidx>(i.op(2)));
const varidx & i1 = ex_to<varidx>(i.op(1));
const varidx & i2 = ex_to<varidx>(i.op(2));
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
/** Automatic symbolic evaluation of an indexed metric tensor. */
ex spinmetric::eval_indexed(const basic & i) const
{
- GINAC_ASSERT(is_of_type(i, indexed));
+ GINAC_ASSERT(is_a<indexed>(i));
GINAC_ASSERT(i.nops() == 3);
- GINAC_ASSERT(is_ex_of_type(i.op(0), spinmetric));
- GINAC_ASSERT(is_ex_of_type(i.op(1), spinidx));
- GINAC_ASSERT(is_ex_of_type(i.op(2), spinidx));
+ GINAC_ASSERT(is_a<spinmetric>(i.op(0)));
+ GINAC_ASSERT(is_a<spinidx>(i.op(1)));
+ GINAC_ASSERT(is_a<spinidx>(i.op(2)));
const spinidx & i1 = ex_to<spinidx>(i.op(1));
const spinidx & i2 = ex_to<spinidx>(i.op(2));
// 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
/** Automatic symbolic evaluation of an indexed epsilon tensor. */
ex tensepsilon::eval_indexed(const basic & i) const
{
- GINAC_ASSERT(is_of_type(i, indexed));
+ GINAC_ASSERT(is_a<indexed>(i));
GINAC_ASSERT(i.nops() > 1);
- GINAC_ASSERT(is_ex_of_type(i.op(0), tensepsilon));
+ GINAC_ASSERT(is_a<tensepsilon>(i.op(0)));
// 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)) {
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_ex_of_type(*self, indexed));
- GINAC_ASSERT(is_ex_of_type(*other, indexed));
- GINAC_ASSERT(self->nops() == 3);
- GINAC_ASSERT(is_ex_of_type(self->op(0), tensdelta));
-
- // 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;
again:
if (self_idx->is_symbolic()) {
- for (int i=1; i<other->nops(); i++) {
+ 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 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);
+ *other = other->subs(other_idx == free_idx->replace_dim(min_dim));
+ *self = _ex1; // *other is assigned first because assigning *self invalidates free_idx
+ 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;
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
{
- GINAC_ASSERT(is_ex_of_type(*self, indexed));
- GINAC_ASSERT(is_ex_of_type(*other, indexed));
+ GINAC_ASSERT(is_a<indexed>(*self));
+ GINAC_ASSERT(is_a<indexed>(*other));
GINAC_ASSERT(self->nops() == 3);
- GINAC_ASSERT(is_ex_of_type(self->op(0), tensmetric));
+ GINAC_ASSERT(is_a<tensmetric>(self->op(0)));
// If contracting with the delta tensor, let the delta do it
// (don't raise/lower delta indices)
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 (int 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. */
bool spinmetric::contract_with(exvector::iterator self, exvector::iterator other, exvector & v) const
{
- GINAC_ASSERT(is_ex_of_type(*self, indexed));
- GINAC_ASSERT(is_ex_of_type(*other, indexed));
+ GINAC_ASSERT(is_a<indexed>(*self));
+ GINAC_ASSERT(is_a<indexed>(*other));
GINAC_ASSERT(self->nops() == 3);
- GINAC_ASSERT(is_ex_of_type(self->op(0), spinmetric));
+ GINAC_ASSERT(is_a<spinmetric>(self->op(0)));
// Contractions between spinor metrics
if (is_ex_of_type(other->op(0), spinmetric)) {
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;
}
}
again:
if (self_idx->is_symbolic()) {
- for (int i=1; i<other->nops(); i++) {
+ 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 = (static_cast<const spinidx *>(self_idx)->is_covariant() ? sign : -sign);
+ // index in second object (assign *self last because this
+ // invalidates free_idx)
*other = other->subs(other_idx == *free_idx);
+ *self = (static_cast<const spinidx *>(self_idx)->is_covariant() ? sign : -sign);
return true;
}
}
return false;
}
+/** Contraction of epsilon tensor with something else. */
+bool tensepsilon::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(is_a<tensepsilon>(self->op(0)));
+ unsigned num = self->nops() - 1;
+
+ if (is_ex_exactly_of_type(other->op(0), tensepsilon) && num+1 == other->nops()) {
+
+ // Contraction of two epsilon tensors is a determinant
+ bool variance = is_a<varidx>(self->op(1));
+ matrix M(num, num);
+ for (unsigned i=0; i<num; i++) {
+ for (unsigned j=0; j<num; j++) {
+ if (minkowski)
+ M(i, j) = lorentz_g(self->op(i+1), other->op(j+1), pos_sig);
+ else if (variance)
+ M(i, j) = metric_tensor(self->op(i+1), other->op(j+1));
+ else
+ M(i, j) = delta_tensor(self->op(i+1), other->op(j+1));
+ }
+ }
+ int sign = minkowski ? -1 : 1;
+ *self = sign * M.determinant().simplify_indexed();
+ *other = _ex1;
+ return true;
+ }
+
+ return false;
+}
+
//////////
// global functions
//////////
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);
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);
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