From c532971f9e99886781437912ae1655719284ac2f Mon Sep 17 00:00:00 2001 From: Richard Kreckel Date: Sat, 31 Oct 2015 17:02:14 +0100 Subject: [PATCH 1/1] Remove unfinished code for hash table-based expairseq. This is unfinished code by A.F. Later generations don't ever seem to have tinkered much with it. ;-) --- ginac/expairseq.cpp | 587 +++----------------------------------------- ginac/expairseq.h | 40 --- 2 files changed, 28 insertions(+), 599 deletions(-) diff --git a/ginac/expairseq.cpp b/ginac/expairseq.cpp index 9ef8afa9..18aba0db 100644 --- a/ginac/expairseq.cpp +++ b/ginac/expairseq.cpp @@ -34,9 +34,6 @@ #include "indexed.h" #include -#if EXPAIRSEQ_USE_HASHTAB -#include -#endif // EXPAIRSEQ_USE_HASHTAB #include #include #include @@ -70,40 +67,10 @@ public: // public expairseq::expairseq() -#if EXPAIRSEQ_USE_HASHTAB - : hashtabsize(0) -#endif // EXPAIRSEQ_USE_HASHTAB {} // protected -#if 0 -/** For use by copy ctor and assignment operator. */ -void expairseq::copy(const expairseq &other) -{ - seq = other.seq; - overall_coeff = other.overall_coeff; -#if EXPAIRSEQ_USE_HASHTAB - // copy hashtab - hashtabsize = other.hashtabsize; - if (hashtabsize!=0) { - hashmask = other.hashmask; - hashtab.resize(hashtabsize); - epvector::const_iterator osb = other.seq.begin(); - for (unsigned i=0; i 0) { - c.s << std::string(level + c.delta_indent, ' ') - << "bin " << i << " with entries "; - for (epplist::const_iterator it=hashtab[i].begin(); - it!=hashtab[i].end(); ++it) { - c.s << *it-seq.begin() << " "; - ++this_bin_fill; - } - c.s << std::endl; - cum_fill += this_bin_fill; - cum_fill_sq += this_bin_fill*this_bin_fill; - } - if (this_bin_fill0) - fact *= k; - double prob = std::pow(lambda,k)/fact * std::exp(-lambda); - cum_prob += prob; - c.s << std::string(level + c.delta_indent, ' ') << "bins with " << k << " entries: " - << int(1000.0*count[k]/hashtabsize)/10.0 << "% (expected: " - << int(prob*1000)/10.0 << ")" << std::endl; - } - c.s << std::string(level + c.delta_indent, ' ') << "bins with more entries: " - << int(1000.0*count[MAXCOUNT]/hashtabsize)/10.0 << "% (expected: " - << int((1-cum_prob)*1000)/10.0 << ")" << std::endl; - - c.s << std::string(level + c.delta_indent, ' ') << "variance: " - << 1.0/hashtabsize*cum_fill_sq-(1.0/hashtabsize*cum_fill)*(1.0/hashtabsize*cum_fill) - << std::endl; - c.s << std::string(level + c.delta_indent, ' ') << "average fill: " - << (1.0*cum_fill)/hashtabsize - << " (should be equal to " << (1.0*seq.size())/hashtabsize << ")" << std::endl; -#endif // EXPAIRSEQ_USE_HASHTAB } bool expairseq::info(unsigned inf) const @@ -494,54 +408,20 @@ int expairseq::compare_same_type(const basic &other) const if (cmpval!=0) return cmpval; -#if EXPAIRSEQ_USE_HASHTAB - GINAC_ASSERT(hashtabsize==o.hashtabsize); - if (hashtabsize==0) { -#endif // EXPAIRSEQ_USE_HASHTAB - epvector::const_iterator cit1 = seq.begin(); - epvector::const_iterator cit2 = o.seq.begin(); - epvector::const_iterator last1 = seq.end(); - epvector::const_iterator last2 = o.seq.end(); + epvector::const_iterator cit1 = seq.begin(); + epvector::const_iterator cit2 = o.seq.begin(); + epvector::const_iterator last1 = seq.end(); + epvector::const_iterator last2 = o.seq.end(); - for (; (cit1!=last1)&&(cit2!=last2); ++cit1, ++cit2) { - cmpval = (*cit1).compare(*cit2); - if (cmpval!=0) return cmpval; - } + for (; (cit1!=last1)&&(cit2!=last2); ++cit1, ++cit2) { + cmpval = (*cit1).compare(*cit2); + if (cmpval!=0) return cmpval; + } - GINAC_ASSERT(cit1==last1); - GINAC_ASSERT(cit2==last2); + GINAC_ASSERT(cit1==last1); + GINAC_ASSERT(cit2==last2); - return 0; -#if EXPAIRSEQ_USE_HASHTAB - } - - // compare number of elements in each hashtab entry - for (unsigned i=0; i0) { - const epplist &eppl1 = hashtab[i]; - const epplist &eppl2 = o.hashtab[i]; - epplist::const_iterator it1 = eppl1.begin(); - epplist::const_iterator it2 = eppl2.begin(); - while (it1!=eppl1.end()) { - cmpval = (*(*it1)).compare(*(*it2)); - if (cmpval!=0) - return cmpval; - ++it1; - ++it2; - } - } - } - - return 0; // equal -#endif // EXPAIRSEQ_USE_HASHTAB + return 0; } bool expairseq::is_equal_same_type(const basic &other) const @@ -556,56 +436,17 @@ bool expairseq::is_equal_same_type(const basic &other) const if (!overall_coeff.is_equal(o.overall_coeff)) return false; -#if EXPAIRSEQ_USE_HASHTAB - // compare number of elements in each hashtab entry - if (hashtabsize!=o.hashtabsize) { - std::cout << "this:" << std::endl; - print(print_tree(std::cout)); - std::cout << "other:" << std::endl; - other.print(print_tree(std::cout)); - } - - GINAC_ASSERT(hashtabsize==o.hashtabsize); - - if (hashtabsize==0) { -#endif // EXPAIRSEQ_USE_HASHTAB - epvector::const_iterator cit1 = seq.begin(); - epvector::const_iterator cit2 = o.seq.begin(); - epvector::const_iterator last1 = seq.end(); - - while (cit1!=last1) { - if (!(*cit1).is_equal(*cit2)) return false; - ++cit1; - ++cit2; - } + epvector::const_iterator cit1 = seq.begin(); + epvector::const_iterator cit2 = o.seq.begin(); + epvector::const_iterator last1 = seq.end(); - return true; -#if EXPAIRSEQ_USE_HASHTAB - } - - for (unsigned i=0; i0) { - const epplist &eppl1 = hashtab[i]; - const epplist &eppl2 = o.hashtab[i]; - epplist::const_iterator it1 = eppl1.begin(); - epplist::const_iterator it2 = eppl2.begin(); - while (it1!=eppl1.end()) { - if (!(*(*it1)).is_equal(*(*it2))) return false; - ++it1; - ++it2; - } - } - } - return true; -#endif // EXPAIRSEQ_USE_HASHTAB } unsigned expairseq::return_type() const @@ -620,11 +461,9 @@ unsigned expairseq::calchash() const const epvector::const_iterator end = seq.end(); while (i != end) { v ^= i->rest.gethash(); -#if !EXPAIRSEQ_USE_HASHTAB // rotation spoils commutativity! v = rotate_left(v); v ^= i->coeff.gethash(); -#endif // !EXPAIRSEQ_USE_HASHTAB ++i; } @@ -741,9 +580,6 @@ ex expairseq::recombine_pair_to_ex(const expair &p) const bool expairseq::expair_needs_further_processing(epp it) { -#if EXPAIRSEQ_USE_HASHTAB - //# error "FIXME: expair_needs_further_processing not yet implemented for hashtabs, sorry. A.F." -#endif // EXPAIRSEQ_USE_HASHTAB return false; } @@ -785,70 +621,30 @@ void expairseq::construct_from_2_ex_via_exvector(const ex &lh, const ex &rh) v.push_back(lh); v.push_back(rh); construct_from_exvector(v); -#if EXPAIRSEQ_USE_HASHTAB - GINAC_ASSERT((hashtabsize==0)||(hashtabsize>=minhashtabsize)); - GINAC_ASSERT(hashtabsize==calc_hashtabsize(seq.size())); -#endif // EXPAIRSEQ_USE_HASHTAB } void expairseq::construct_from_2_ex(const ex &lh, const ex &rh) { if (typeid(ex_to(lh)) == typeid(*this)) { if (typeid(ex_to(rh)) == typeid(*this)) { -#if EXPAIRSEQ_USE_HASHTAB - unsigned totalsize = ex_to(lh).seq.size() + - ex_to(rh).seq.size(); - if (calc_hashtabsize(totalsize)!=0) { - construct_from_2_ex_via_exvector(lh,rh); - } else { -#endif // EXPAIRSEQ_USE_HASHTAB - if (is_a(lh) && lh.info(info_flags::has_indices) && - rh.info(info_flags::has_indices)) { - ex newrh=rename_dummy_indices_uniquely(lh, rh); - construct_from_2_expairseq(ex_to(lh), - ex_to(newrh)); - } - else - construct_from_2_expairseq(ex_to(lh), - ex_to(rh)); -#if EXPAIRSEQ_USE_HASHTAB + if (is_a(lh) && lh.info(info_flags::has_indices) && + rh.info(info_flags::has_indices)) { + ex newrh=rename_dummy_indices_uniquely(lh, rh); + construct_from_2_expairseq(ex_to(lh), + ex_to(newrh)); } -#endif // EXPAIRSEQ_USE_HASHTAB + else + construct_from_2_expairseq(ex_to(lh), + ex_to(rh)); return; } else { -#if EXPAIRSEQ_USE_HASHTAB - unsigned totalsize = ex_to(lh).seq.size()+1; - if (calc_hashtabsize(totalsize)!=0) { - construct_from_2_ex_via_exvector(lh, rh); - } else { -#endif // EXPAIRSEQ_USE_HASHTAB - construct_from_expairseq_ex(ex_to(lh), rh); -#if EXPAIRSEQ_USE_HASHTAB - } -#endif // EXPAIRSEQ_USE_HASHTAB + construct_from_expairseq_ex(ex_to(lh), rh); return; } } else if (typeid(ex_to(rh)) == typeid(*this)) { -#if EXPAIRSEQ_USE_HASHTAB - unsigned totalsize=ex_to(rh).seq.size()+1; - if (calc_hashtabsize(totalsize)!=0) { - construct_from_2_ex_via_exvector(lh,rh); - } else { -#endif // EXPAIRSEQ_USE_HASHTAB - construct_from_expairseq_ex(ex_to(rh),lh); -#if EXPAIRSEQ_USE_HASHTAB - } -#endif // EXPAIRSEQ_USE_HASHTAB - return; - } - -#if EXPAIRSEQ_USE_HASHTAB - if (calc_hashtabsize(2)!=0) { - construct_from_2_ex_via_exvector(lh,rh); + construct_from_expairseq_ex(ex_to(rh),lh); return; } - hashtabsize = 0; -#endif // EXPAIRSEQ_USE_HASHTAB if (is_exactly_a(lh)) { if (is_exactly_a(rh)) { @@ -1013,12 +809,8 @@ void expairseq::construct_from_exvector(const exvector &v) // (same for (+,*) -> (*,^) make_flat(v); -#if EXPAIRSEQ_USE_HASHTAB - combine_same_terms(); -#else canonicalize(); combine_same_terms_sorted_seq(); -#endif // EXPAIRSEQ_USE_HASHTAB } void expairseq::construct_from_epvector(const epvector &v, bool do_index_renaming) @@ -1029,12 +821,8 @@ void expairseq::construct_from_epvector(const epvector &v, bool do_index_renamin // same for (+,*) -> (*,^) make_flat(v, do_index_renaming); -#if EXPAIRSEQ_USE_HASHTAB - combine_same_terms(); -#else canonicalize(); combine_same_terms_sorted_seq(); -#endif // EXPAIRSEQ_USE_HASHTAB } /** Combine this expairseq with argument exvector. @@ -1207,315 +995,6 @@ void expairseq::combine_same_terms_sorted_seq() } } -#if EXPAIRSEQ_USE_HASHTAB - -unsigned expairseq::calc_hashtabsize(unsigned sz) const -{ - unsigned size; - unsigned nearest_power_of_2 = 1 << log2(sz); - // if (nearest_power_of_2 < maxhashtabsize/hashtabfactor) { - // size = nearest_power_of_2*hashtabfactor; - size = nearest_power_of_2/hashtabfactor; - if (size(e)) { - hashindex = hashmask; - } else { - hashindex = e.gethash() & hashmask; - // last hashtab entry is reserved for numerics - if (hashindex==hashmask) hashindex = 0; - } - GINAC_ASSERT((hashindexrest); - epplist &eppl = hashtab[hashindex]; - epplist::iterator epplit = eppl.begin(); - bool erased = false; - while (epplit!=eppl.end()) { - if (*epplit == element) { - eppl.erase(epplit); - erased = true; - break; - } - ++epplit; - } - GINAC_ASSERT(erased); - } - GINAC_ASSERT(erased); -} - -void expairseq::move_hashtab_entry(epvector::const_iterator oldpos, - epvector::iterator newpos) -{ - GINAC_ASSERT(hashtabsize!=0); - - // calculate hashindex of element which was moved - unsigned hashindex=calc_hashindex((*newpos).rest); - - // find it in hashtab and modify it - epplist &eppl = hashtab[hashindex]; - epplist::iterator epplit = eppl.begin(); - while (epplit!=eppl.end()) { - if (*epplit == oldpos) { - *epplit = newpos; - break; - } - ++epplit; - } - GINAC_ASSERT(epplit!=eppl.end()); -} - -void expairseq::sorted_insert(epplist &eppl, epvector::const_iterator elem) -{ - epplist::const_iterator current = eppl.begin(); - while ((current!=eppl.end()) && ((*current)->is_less(*elem))) { - ++current; - } - eppl.insert(current,elem); -} - -void expairseq::build_hashtab_and_combine(epvector::iterator &first_numeric, - epvector::iterator &last_non_zero, - std::vector &touched, - unsigned &number_of_zeroes) -{ - epp current = seq.begin(); - - while (current!=first_numeric) { - if (is_exactly_a(current->rest)) { - --first_numeric; - iter_swap(current,first_numeric); - } else { - // calculate hashindex - unsigned currenthashindex = calc_hashindex(current->rest); - - // test if there is already a matching expair in the hashtab-list - epplist &eppl=hashtab[currenthashindex]; - epplist::iterator epplit = eppl.begin(); - while (epplit!=eppl.end()) { - if (current->rest.is_equal((*epplit)->rest)) - break; - ++epplit; - } - if (epplit==eppl.end()) { - // no matching expair found, append this to end of list - sorted_insert(eppl,current); - ++current; - } else { - // epplit points to a matching expair, combine it with current - (*epplit)->coeff = ex_to((*epplit)->coeff). - add_dyn(ex_to(current->coeff)); - - // move obsolete current expair to end by swapping with last_non_zero element - // if this was a numeric, it is swapped with the expair before first_numeric - iter_swap(current,last_non_zero); - --first_numeric; - if (first_numeric!=last_non_zero) iter_swap(first_numeric,current); - --last_non_zero; - ++number_of_zeroes; - // test if combined term has coeff 0 and can be removed is done later - touched[(*epplit)-seq.begin()] = true; - } - } - } -} - -void expairseq::drop_coeff_0_terms(epvector::iterator &first_numeric, - epvector::iterator &last_non_zero, - std::vector &touched, - unsigned &number_of_zeroes) -{ - // move terms with coeff 0 to end and remove them from hashtab - // check only those elements which have been touched - epp current = seq.begin(); - size_t i = 0; - while (current!=first_numeric) { - if (!touched[i]) { - ++current; - ++i; - } else if (!ex_to((*current).coeff).is_zero()) { - ++current; - ++i; - } else { - remove_hashtab_entry(current); - - // move element to the end, unless it is already at the end - if (current!=last_non_zero) { - iter_swap(current,last_non_zero); - --first_numeric; - bool numeric_swapped = first_numeric!=last_non_zero; - if (numeric_swapped) - iter_swap(first_numeric,current); - epvector::iterator changed_entry; - - if (numeric_swapped) - changed_entry = first_numeric; - else - changed_entry = last_non_zero; - - --last_non_zero; - ++number_of_zeroes; - - if (first_numeric!=current) { - - // change entry in hashtab which referred to first_numeric or last_non_zero to current - move_hashtab_entry(changed_entry,current); - touched[current-seq.begin()] = touched[changed_entry-seq.begin()]; - } - } else { - --first_numeric; - --last_non_zero; - ++number_of_zeroes; - } - } - } - GINAC_ASSERT(i==current-seq.begin()); -} - -/** True if one of the coeffs vanishes, otherwise false. - * This would be an invariant violation, so this should only be used for - * debugging purposes. */ -bool expairseq::has_coeff_0() const -{ - epvector::const_iterator i = seq.begin(), end = seq.end(); - while (i != end) { - if (i->coeff.is_zero()) - return true; - ++i; - } - return false; -} - -void expairseq::add_numerics_to_hashtab(epvector::iterator first_numeric, - epvector::const_iterator last_non_zero) -{ - if (first_numeric == seq.end()) return; // no numerics - - epvector::const_iterator current = first_numeric, last = last_non_zero + 1; - while (current != last) { - sorted_insert(hashtab[hashmask], current); - ++current; - } -} - -void expairseq::combine_same_terms() -{ - // combine same terms, drop term with coeff 0, move numerics to end - - // calculate size of hashtab - hashtabsize = calc_hashtabsize(seq.size()); - - // hashtabsize is a power of 2 - hashmask = hashtabsize-1; - - // allocate hashtab - hashtab.clear(); - hashtab.resize(hashtabsize); - - if (hashtabsize==0) { - canonicalize(); - combine_same_terms_sorted_seq(); - GINAC_ASSERT(!has_coeff_0()); - return; - } - - // iterate through seq, move numerics to end, - // fill hashtab and combine same terms - epvector::iterator first_numeric = seq.end(); - epvector::iterator last_non_zero = seq.end()-1; - - size_t num = seq.size(); - std::vector touched(num); - - unsigned number_of_zeroes = 0; - - GINAC_ASSERT(!has_coeff_0()); - build_hashtab_and_combine(first_numeric,last_non_zero,touched,number_of_zeroes); - - // there should not be any terms with coeff 0 from the beginning, - // so it should be safe to skip this step - if (number_of_zeroes!=0) { - drop_coeff_0_terms(first_numeric,last_non_zero,touched,number_of_zeroes); - } - - add_numerics_to_hashtab(first_numeric,last_non_zero); - - // pop zero elements - for (unsigned i=0; i 0) return 1; // not canonicalized -#endif // EXPAIRSEQ_USE_HASHTAB - epvector::const_iterator it = seq.begin(), itend = seq.end(); epvector::const_iterator it_last = it; for (++it; it!=itend; it_last=it, ++it) { @@ -1748,10 +1223,4 @@ std::auto_ptr expairseq::subschildren(const exmap & m, unsigned option // static member variables ////////// -#if EXPAIRSEQ_USE_HASHTAB -unsigned expairseq::maxhashtabsize = 0x4000000U; -unsigned expairseq::minhashtabsize = 0x1000U; -unsigned expairseq::hashtabfactor = 1; -#endif // EXPAIRSEQ_USE_HASHTAB - } // namespace GiNaC diff --git a/ginac/expairseq.h b/ginac/expairseq.h index 82489f8c..6e98bbfc 100644 --- a/ginac/expairseq.h +++ b/ginac/expairseq.h @@ -34,17 +34,6 @@ namespace GiNaC { -/** Using hash tables can potentially enhance the asymptotic behaviour of - * combining n terms into one large sum (or n terms into one large product) - * from O(n*log(n)) to about O(n). There are, however, several drawbacks. - * The constant in front of O(n) is quite large, when copying such an object - * one also has to copy the has table, comparison is quite expensive because - * there is no ordering any more, it doesn't help at all when combining two - * expairseqs because due to the presorted nature the behaviour would be - * O(n) anyways, the code is quite messy, etc, etc. The code is here as - * an example for following generations to tinker with. */ -#define EXPAIRSEQ_USE_HASHTAB 0 - typedef std::vector epvector; ///< expair-vector typedef epvector::iterator epp; ///< expair-vector pointer typedef std::list epplist; ///< list of expair-vector pointers @@ -133,27 +122,6 @@ protected: void make_flat(const epvector & v, bool do_index_renaming = false); void canonicalize(); void combine_same_terms_sorted_seq(); -#if EXPAIRSEQ_USE_HASHTAB - void combine_same_terms(); - unsigned calc_hashtabsize(unsigned sz) const; - unsigned calc_hashindex(const ex & e) const; - void shrink_hashtab(); - void remove_hashtab_entry(epvector::const_iterator element); - void move_hashtab_entry(epvector::const_iterator oldpos, - epvector::iterator newpos); - void sorted_insert(epplist & eppl, epvector::const_iterator elem); - void build_hashtab_and_combine(epvector::iterator & first_numeric, - epvector::iterator & last_non_zero, - vector & touched, - unsigned & number_of_zeroes); - void drop_coeff_0_terms(epvector::iterator & first_numeric, - epvector::iterator & last_non_zero, - vector & touched, - unsigned & number_of_zeroes); - bool has_coeff_0() const; - void add_numerics_to_hashtab(epvector::iterator first_numeric, - epvector::const_iterator last_non_zero); -#endif // EXPAIRSEQ_USE_HASHTAB bool is_canonical() const; std::auto_ptr expandchildren(unsigned options) const; std::auto_ptr evalchildren(int level) const; @@ -164,14 +132,6 @@ protected: protected: epvector seq; ex overall_coeff; -#if EXPAIRSEQ_USE_HASHTAB - epplistvector hashtab; - unsigned hashtabsize; - unsigned hashmask; - static unsigned maxhashtabsize; - static unsigned minhashtabsize; - static unsigned hashtabfactor; -#endif // EXPAIRSEQ_USE_HASHTAB }; /** Class to handle the renaming of dummy indices. It holds a vector of -- 2.44.0