// contraction with symmetric tensor is zero
result += check_equal_simplify(lorentz_eps(mu, nu, rho, sigma) * indexed(d, sy_symm(), mu_co, nu_co), 0);
result += check_equal_simplify(lorentz_eps(mu, nu, rho, sigma) * indexed(d, sy_symm(), nu_co, sigma_co, rho_co), 0);
- ex e = lorentz_eps(mu, nu, rho, sigma) * indexed(d, sy_symm(), mu_co, tau);
- result += check_equal_simplify(e, e);
+ result += check_equal_simplify(lorentz_eps(mu, nu, rho, sigma) * indexed(d, mu_co) * indexed(d, nu_co), 0);
+ result += check_equal_simplify(lorentz_eps(mu_co, nu, rho, sigma) * indexed(d, mu) * indexed(d, nu_co), 0);
+ ex e = lorentz_eps(mu, nu, rho, sigma) * indexed(d, mu_co) - lorentz_eps(mu_co, nu, rho, sigma) * indexed(d, mu);
+ result += check_equal_simplify(e, 0);
// contractions of epsilon tensors
result += check_equal_simplify(lorentz_eps(mu, nu, rho, sigma) * lorentz_eps(mu_co, nu_co, rho_co, sigma_co), -24);
unsigned result = 0;
idx i(symbol("i"), 3), j(symbol("j"), 3), k(symbol("k"), 3), l(symbol("l"), 3);
- symbol A("A"), B("B");
+ symbol A("A"), B("B"), C("C");
ex e;
result += check_equal(indexed(A, sy_symm(), i, j), indexed(A, sy_symm(), j, i));
result += check_equal(symmetrize(e), 0);
result += check_equal(antisymmetrize(e), e);
+ e = (indexed(A, sy_anti(), i, j, k, l) * (indexed(B, j) * indexed(C, k) + indexed(B, k) * indexed(C, j)) + indexed(B, i, l)).expand();
+ result += check_equal_simplify(e, indexed(B, i, l));
+
return result;
}
unsigned result = 0;
symbol psi("psi");
- spinidx A(symbol("A"), 2), B(symbol("B"), 2), C(symbol("C"), 2);
+ spinidx A(symbol("A")), B(symbol("B")), C(symbol("C")), D(symbol("D"));
ex A_co = A.toggle_variance(), B_co = B.toggle_variance();
ex e;
result += check_equal_simplify(e, -indexed(psi, A_co));
e = spinor_metric(A_co, B_co) * indexed(psi, A);
result += check_equal_simplify(e, indexed(psi, B_co));
+ e = spinor_metric(D, A) * spinor_metric(A_co, B_co) * spinor_metric(B, C) - spinor_metric(D, A_co) * spinor_metric(A, B_co) * spinor_metric(B, C);
+ result += check_equal_simplify(e, 0);
return result;
}
static unsigned dummy_check(void)
{
- // check dummy index renaming
+ // check dummy index renaming/repositioning
unsigned result = 0;
e = indexed(p, mu, mu.toggle_variance()) - indexed(p, nu, nu.toggle_variance());
result += check_equal_simplify(e, 0);
+ e = indexed(p, mu.toggle_variance(), nu, mu) * indexed(q, i)
+ - indexed(p, mu, nu, mu.toggle_variance()) * indexed(q, i);
+ result += check_equal_simplify(e, 0);
+
+ e = indexed(p, mu, mu.toggle_variance()) - indexed(p, nu.toggle_variance(), nu);
+ result += check_equal_simplify(e, 0);
+ e = indexed(p, mu.toggle_variance(), mu) - indexed(p, nu, nu.toggle_variance());
+ result += check_equal_simplify(e, 0);
+
return result;
}
#include "mul.h"
#include "ncmul.h"
#include "power.h"
+#include "relational.h"
#include "symmetry.h"
#include "operators.h"
#include "lst.h"
/** Rename dummy indices in an expression.
*
- * @param e Expression to be worked on
+ * @param e Expression to work on
* @param local_dummy_indices The set of dummy indices that appear in the
* expression "e"
* @param global_dummy_indices The set of dummy indices that have appeared
}
}
+/** Given a set of indices, extract those of class varidx. */
+static void find_variant_indices(const exvector & v, exvector & variant_indices)
+{
+ exvector::const_iterator it1, itend;
+ for (it1 = v.begin(), itend = v.end(); it1 != itend; ++it1) {
+ if (is_exactly_a<varidx>(*it1))
+ variant_indices.push_back(*it1);
+ }
+}
+
+/** Raise/lower dummy indices in a single indexed objects to canonicalize their
+ * variance.
+ *
+ * @param e Object to work on
+ * @param variant_dummy_indices The set of indices that might need repositioning (will be changed by this function)
+ * @param moved_indices The set of indices that have been repositioned (will be changed by this function)
+ * @return true if 'e' was changed */
+bool reposition_dummy_indices(ex & e, exvector & variant_dummy_indices, exvector & moved_indices)
+{
+ bool something_changed = false;
+
+ // 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) {
+ if (!is_exactly_a<varidx>(*it2))
+ continue;
+
+ exvector::iterator vit, vitend;
+ 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
+ ));
+ 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);
+ goto next_index;
+ }
+ }
+
+ 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());
+ 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;
+ }
+ }
+
+next_index: ;
+ }
+
+ return something_changed;
+}
+
+/* Ordering that only compares the base expressions of indexed objects. */
+struct ex_base_is_less : public std::binary_function<ex, ex, bool> {
+ bool operator() (const ex &lh, const ex &rh) const
+ {
+ return (is_a<indexed>(lh) ? lh.op(0) : lh).compare(is_a<indexed>(rh) ? rh.op(0) : rh) < 0;
+ }
+};
+
/** Simplify product of indexed expressions (commutative, noncommutative and
* simple squares), return list of free indices. */
ex simplify_indexed_product(const ex & e, exvector & free_indices, exvector & dummy_indices, const scalar_products & sp)
// Find free indices (concatenate them all and call find_free_and_dummy())
// and all dummy indices that appear
exvector un, individual_dummy_indices;
- it1 = v.begin(); itend = v.end();
- while (it1 != itend) {
+ for (it1 = v.begin(), itend = v.end(); it1 != itend; ++it1) {
exvector free_indices_of_factor;
if (is_a<indexed>(*it1)) {
exvector dummy_indices_of_factor;
} else
free_indices_of_factor = it1->get_free_indices();
un.insert(un.end(), free_indices_of_factor.begin(), free_indices_of_factor.end());
- it1++;
}
exvector local_dummy_indices;
find_free_and_dummy(un, free_indices, local_dummy_indices);
local_dummy_indices.insert(local_dummy_indices.end(), individual_dummy_indices.begin(), individual_dummy_indices.end());
+ // Filter out the dummy indices with variance
+ exvector variant_dummy_indices;
+ find_variant_indices(local_dummy_indices, variant_dummy_indices);
+
+ // Any indices with variance present at all?
+ if (!variant_dummy_indices.empty()) {
+
+ // Yes, bring the product into a canonical order that only depends on
+ // the base expressions of indexed objects
+ if (!non_commutative)
+ std::sort(v.begin(), v.end(), ex_base_is_less());
+
+ exvector moved_indices;
+
+ // Iterate over all indexed objects in the product
+ for (it1 = v.begin(), itend = v.end(); it1 != itend; ++it1) {
+ if (!is_a<indexed>(*it1))
+ continue;
+
+ if (reposition_dummy_indices(*it1, variant_dummy_indices, moved_indices))
+ something_changed = true;
+ }
+ }
+
ex r;
if (something_changed)
r = non_commutative ? ex(ncmul(v, true)) : ex(mul(v));
ex e_expanded = e.expand();
// Simplification of single indexed object: just find the free indices
- // and perform dummy index renaming
+ // and perform dummy index renaming/repositioning
if (is_a<indexed>(e_expanded)) {
+
+ // Find the dummy indices
const indexed &i = ex_to<indexed>(e_expanded);
exvector local_dummy_indices;
find_free_and_dummy(i.seq.begin() + 1, i.seq.end(), free_indices, local_dummy_indices);
+
+ // Filter out the dummy indices with variance
+ exvector variant_dummy_indices;
+ find_variant_indices(local_dummy_indices, variant_dummy_indices);
+
+ // Any indices with variance present at all?
+ if (!variant_dummy_indices.empty()) {
+
+ // Yes, reposition them
+ exvector moved_indices;
+ reposition_dummy_indices(e_expanded, variant_dummy_indices, moved_indices);
+ }
+
+ // Rename the dummy indices
return rename_dummy_indices(e_expanded, dummy_indices, local_dummy_indices);
}
}
}
+ if (sum.is_zero()) {
+ free_indices.clear();
+ return sum;
+ }
+
+ // Symmetrizing over the dummy indices may cancel terms
+ int num_terms_orig = (is_a<add>(sum) ? sum.nops() : 1);
+ if (num_terms_orig > 1 && dummy_indices.size() >= 2) {
+ lst dummy_syms;
+ for (int i=0; i<dummy_indices.size(); i++)
+ dummy_syms.append(dummy_indices[i].op(0));
+ ex sum_symm = sum.symmetrize(dummy_syms);
+ if (sum_symm.is_zero()) {
+ free_indices.clear();
+ return _ex0;
+ }
+ int num_terms = (is_a<add>(sum_symm) ? sum_symm.nops() : 1);
+ if (num_terms < num_terms_orig)
+ return sum_symm;
+ }
+
return sum;
}
projects / ginac.git / commitdiff