* methods for series expansion. */
/*
- * GiNaC Copyright (C) 1999-2007 Johannes Gutenberg University Mainz, Germany
+ * GiNaC Copyright (C) 1999-2008 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
// holds ldegrees of the series of individual factors
std::vector<int> ldegrees;
+ std::vector<bool> ldegree_redo;
// find minimal degrees
const epvector::const_iterator itbeg = seq.begin();
const epvector::const_iterator itend = seq.end();
+ // first round: obtain a bound up to which minimal degrees have to be
+ // considered
for (epvector::const_iterator it=itbeg; it!=itend; ++it) {
ex expon = it->coeff;
}
int real_ldegree = 0;
+ bool flag_redo = false;
try {
real_ldegree = buf.expand().ldegree(sym-r.rhs());
} catch (std::runtime_error) {}
if (real_ldegree == 0) {
+ if ( factor < 0 ) {
+ // This case must terminate, otherwise we would have division by
+ // zero.
+ int orderloop = 0;
+ do {
+ orderloop++;
+ real_ldegree = buf.series(r, orderloop, options).ldegree(sym);
+ } while (real_ldegree == orderloop);
+ } else {
+ // Here it is possible that buf does not have a ldegree, therefore
+ // check only if ldegree is negative, otherwise reconsider the case
+ // in the second round.
+ real_ldegree = buf.series(r, 0, options).ldegree(sym);
+ if (real_ldegree == 0)
+ flag_redo = true;
+ }
+ }
+
+ ldegrees.push_back(factor * real_ldegree);
+ ldegree_redo.push_back(flag_redo);
+ }
+
+ int degbound = order-std::accumulate(ldegrees.begin(), ldegrees.end(), 0);
+ // Second round: determine the remaining positive ldegrees by the series
+ // method.
+ // here we can ignore ldegrees larger than degbound
+ size_t j = 0;
+ for (epvector::const_iterator it=itbeg; it!=itend; ++it) {
+ if ( ldegree_redo[j] ) {
+ ex expon = it->coeff;
+ int factor = 1;
+ ex buf;
+ if (expon.info(info_flags::integer)) {
+ buf = it->rest;
+ factor = ex_to<numeric>(expon).to_int();
+ } else {
+ buf = recombine_pair_to_ex(*it);
+ }
+ int real_ldegree = 0;
int orderloop = 0;
do {
orderloop++;
real_ldegree = buf.series(r, orderloop, options).ldegree(sym);
- } while (real_ldegree == orderloop);
+ } while ((real_ldegree == orderloop)
+ && ( factor*real_ldegree < degbound));
+ ldegrees[j] = factor * real_ldegree;
+ degbound -= factor * real_ldegree;
}
-
- ldegrees.push_back(factor * real_ldegree);
+ j++;
}
int degsum = std::accumulate(ldegrees.begin(), ldegrees.end(), 0);
else
throw (std::logic_error("ex::series(): expansion point has unknown type"));
- try {
- e = bp->series(rel_, order, options);
- } catch (std::exception &x) {
- throw (std::logic_error(std::string("unable to compute series (") + x.what() + ")"));
- }
+ e = bp->series(rel_, order, options);
return e;
}