* Implementation of GiNaC's indices. */
/*
- * GiNaC Copyright (C) 1999-2003 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2004 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
GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(varidx, idx,
print_func<print_context>(&varidx::do_print).
- // print_latex inherited from idx
+ print_func<print_latex>(&varidx::do_print_latex).
print_func<print_tree>(&varidx::do_print_tree))
GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(spinidx, varidx,
ex idx::map(map_function & f) const
{
- idx *copy = duplicate();
- copy->setflag(status_flags::dynallocated);
- copy->clearflag(status_flags::hash_calculated);
- copy->value = f(value);
- return *copy;
+ const ex &mapped_value = f(value);
+ if (are_ex_trivially_equal(value, mapped_value))
+ return *this;
+ else {
+ idx *copy = duplicate();
+ copy->setflag(status_flags::dynallocated);
+ copy->clearflag(status_flags::hash_calculated);
+ copy->value = mapped_value;
+ return *copy;
+ }
}
/** Returns order relation between two indices of the same type. The order
unsigned idx::calchash() const
{
+ // NOTE: The code in simplify_indexed() assumes that canonically
+ // ordered sequences of indices have the two members of dummy index
+ // pairs lying next to each other. The hash values for indices must
+ // be devised accordingly. The easiest (only?) way to guarantee the
+ // desired ordering is to make indices with the same value have equal
+ // hash keys. That is, the hash values must not depend on the index
+ // dimensions or other attributes (variance etc.).
+ // The compare_same_type() methods will take care of the rest.
unsigned v = golden_ratio_hash(tinfo());
v = rotate_left(v);
v ^= value.gethash();
- v = rotate_left(v);
- v ^= dim.gethash();
// Store calculated hash value only if object is already evaluated
if (flags & status_flags::evaluated) {