+
+ // Is the expression of type something^(-int)?
+ if (!must_expand_basis && !exponent.info(info_flags::negint) && !is_a<add>(basis))
+ return basic::series(r, order, options);
+
+ // Is the expression of type 0^something?
+ if (!must_expand_basis && !basis.subs(r, subs_options::no_pattern).is_zero() && !is_a<add>(basis))
+ return basic::series(r, order, options);
+
+ // Singularity encountered, is the basis equal to (var - point)?
+ if (basis.is_equal(r.lhs() - r.rhs())) {
+ epvector new_seq;
+ if (ex_to<numeric>(exponent).to_int() < order)
+ new_seq.push_back(expair(_ex1, exponent));
+ else
+ new_seq.push_back(expair(Order(_ex1), exponent));
+ return pseries(r, new_seq);
+ }
+
+ // No, expand basis into series
+
+ numeric numexp = ex_to<numeric>(exponent);
+ const ex& sym = r.lhs();
+ // find existing minimal degree
+ int real_ldegree = basis.expand().ldegree(sym-r.rhs());
+ if (real_ldegree == 0) {
+ int orderloop = 0;
+ do {
+ orderloop++;
+ real_ldegree = basis.series(r, orderloop, options).ldegree(sym);
+ } while (real_ldegree == orderloop);
+ }
+
+ if (!(real_ldegree*numexp).is_integer())
+ throw std::runtime_error("pseries::power_const(): trying to assemble a Puiseux series");
+ ex e = basis.series(r, (order + real_ldegree*(1-numexp)).to_int(), options);