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[ginac.git] / ginac / pseries.cpp
index 0fae94bc7360f348879ef3caff8be1e8f0c7eb10..993eacf119f7583903747f2a92577f59fa508841 100644 (file)
@@ -4,7 +4,7 @@
  *  methods for series expansion. */
 
 /*
- *  GiNaC Copyright (C) 1999-2001 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
@@ -21,6 +21,7 @@
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <numeric>
 #include <stdexcept>
 
 #include "pseries.h"
 #include "mul.h"
 #include "power.h"
 #include "relational.h"
+#include "operators.h"
 #include "symbol.h"
-#include "print.h"
 #include "archive.h"
 #include "utils.h"
-#include "debugmsg.h"
 
 namespace GiNaC {
 
-GINAC_IMPLEMENT_REGISTERED_CLASS(pseries, basic)
+GINAC_IMPLEMENT_REGISTERED_CLASS_OPT(pseries, basic,
+  print_func<print_context>(&pseries::do_print).
+  print_func<print_latex>(&pseries::do_print_latex).
+  print_func<print_tree>(&pseries::do_print_tree).
+  print_func<print_python>(&pseries::do_print_python).
+  print_func<print_python_repr>(&pseries::do_print_python_repr))
 
 
 /*
- *  Default ctor, dtor, copy ctor, assignment operator and helpers
+ *  Default constructor
  */
 
-pseries::pseries() : basic(TINFO_pseries)
-{
-       debugmsg("pseries default ctor", LOGLEVEL_CONSTRUCT);
-}
-
-void pseries::copy(const pseries &other)
-{
-       inherited::copy(other);
-       seq = other.seq;
-       var = other.var;
-       point = other.point;
-}
-
-DEFAULT_DESTROY(pseries)
+pseries::pseries() : inherited(TINFO_pseries) { }
 
 
 /*
@@ -68,7 +60,7 @@ DEFAULT_DESTROY(pseries)
 /** Construct pseries from a vector of coefficients and powers.
  *  expair.rest holds the coefficient, expair.coeff holds the power.
  *  The powers must be integers (positive or negative) and in ascending order;
- *  the last coefficient can be Order(_ex1()) to represent a truncated,
+ *  the last coefficient can be Order(_ex1) to represent a truncated,
  *  non-terminating series.
  *
  *  @param rel_  expansion variable and point (must hold a relational)
@@ -76,9 +68,8 @@ DEFAULT_DESTROY(pseries)
  *  @return newly constructed pseries */
 pseries::pseries(const ex &rel_, const epvector &ops_) : basic(TINFO_pseries), seq(ops_)
 {
-       debugmsg("pseries ctor from ex,epvector", LOGLEVEL_CONSTRUCT);
-       GINAC_ASSERT(is_exactly_a<relational>(rel_));
-       GINAC_ASSERT(is_exactly_a<symbol>(rel_.lhs()));
+       GINAC_ASSERT(is_a<relational>(rel_));
+       GINAC_ASSERT(is_a<symbol>(rel_.lhs()));
        point = rel_.rhs();
        var = rel_.lhs();
 }
@@ -88,9 +79,8 @@ pseries::pseries(const ex &rel_, const epvector &ops_) : basic(TINFO_pseries), s
  *  Archiving
  */
 
-pseries::pseries(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
+pseries::pseries(const archive_node &n, lst &sym_lst) : inherited(n, sym_lst)
 {
-       debugmsg("pseries ctor from archive_node", LOGLEVEL_CONSTRUCT);
        for (unsigned int i=0; true; ++i) {
                ex rest;
                ex coeff;
@@ -122,93 +112,118 @@ DEFAULT_UNARCHIVE(pseries)
 // functions overriding virtual functions from base classes
 //////////
 
-void pseries::print(const print_context & c, unsigned level) const
+void pseries::print_series(const print_context & c, const char *openbrace, const char *closebrace, const char *mul_sym, const char *pow_sym, unsigned level) const
 {
-       debugmsg("pseries print", LOGLEVEL_PRINT);
+       if (precedence() <= level)
+               c.s << '(';
+               
+       // objects of type pseries must not have any zero entries, so the
+       // trivial (zero) pseries needs a special treatment here:
+       if (seq.empty())
+               c.s << '0';
 
-       if (is_a<print_tree>(c)) {
+       epvector::const_iterator i = seq.begin(), end = seq.end();
+       while (i != end) {
 
-               c.s << std::string(level, ' ') << class_name()
-                   << std::hex << ", hash=0x" << hashvalue << ", flags=0x" << flags << std::dec
-                   << std::endl;
-               unsigned delta_indent = static_cast<const print_tree &>(c).delta_indent;
-               unsigned num = seq.size();
-               for (unsigned i=0; i<num; ++i) {
-                       seq[i].rest.print(c, level + delta_indent);
-                       seq[i].coeff.print(c, level + delta_indent);
-                       c.s << std::string(level + delta_indent, ' ') << "-----" << std::endl;
-               }
-               var.print(c, level + delta_indent);
-               point.print(c, level + delta_indent);
+               // print a sign, if needed
+               if (i != seq.begin())
+                       c.s << '+';
 
-       } else {
+               if (!is_order_function(i->rest)) {
 
-               if (precedence() <= level)
-                       c.s << "(";
-               
-               std::string par_open = is_a<print_latex>(c) ? "{(" : "(";
-               std::string par_close = is_a<print_latex>(c) ? ")}" : ")";
-               
-               // objects of type pseries must not have any zero entries, so the
-               // trivial (zero) pseries needs a special treatment here:
-               if (seq.empty())
-                       c.s << '0';
-               epvector::const_iterator i = seq.begin(), end = seq.end();
-               while (i != end) {
-                       // print a sign, if needed
-                       if (i != seq.begin())
-                               c.s << '+';
-                       if (!is_order_function(i->rest)) {
-                               // print 'rest', i.e. the expansion coefficient
-                               if (i->rest.info(info_flags::numeric) &&
-                                       i->rest.info(info_flags::positive)) {
-                                       i->rest.print(c);
-                               } else {
-                                       c.s << par_open;
-                                       i->rest.print(c);
-                                       c.s << par_close;
-                               }
-                               // print 'coeff', something like (x-1)^42
-                               if (!i->coeff.is_zero()) {
-                                       if (is_a<print_latex>(c))
-                                               c.s << ' ';
-                                       else
-                                               c.s << '*';
-                                       if (!point.is_zero()) {
-                                               c.s << par_open;
-                                               (var-point).print(c);
-                                               c.s << par_close;
+                       // print 'rest', i.e. the expansion coefficient
+                       if (i->rest.info(info_flags::numeric) &&
+                               i->rest.info(info_flags::positive)) {
+                               i->rest.print(c);
+                       } else {
+                               c.s << openbrace << '(';
+                               i->rest.print(c);
+                               c.s << ')' << closebrace;
+                       }
+
+                       // print 'coeff', something like (x-1)^42
+                       if (!i->coeff.is_zero()) {
+                               c.s << mul_sym;
+                               if (!point.is_zero()) {
+                                       c.s << openbrace << '(';
+                                       (var-point).print(c);
+                                       c.s << ')' << closebrace;
+                               } else
+                                       var.print(c);
+                               if (i->coeff.compare(_ex1)) {
+                                       c.s << pow_sym;
+                                       c.s << openbrace;
+                                       if (i->coeff.info(info_flags::negative)) {
+                                               c.s << '(';
+                                               i->coeff.print(c);
+                                               c.s << ')';
                                        } else
-                                               var.print(c);
-                                       if (i->coeff.compare(_ex1())) {
-                                               c.s << '^';
-                                               if (i->coeff.info(info_flags::negative)) {
-                                                       c.s << par_open;
-                                                       i->coeff.print(c);
-                                                       c.s << par_close;
-                                               } else {
-                                                       if (is_a<print_latex>(c)) {
-                                                               c.s << '{';
-                                                               i->coeff.print(c);
-                                                               c.s << '}';
-                                                       } else
-                                                               i->coeff.print(c);
-                                               }
-                                       }
+                                               i->coeff.print(c);
+                                       c.s << closebrace;
                                }
-                       } else
-                               Order(power(var-point,i->coeff)).print(c);
-                       ++i;
-               }
+                       }
+               } else
+                       Order(power(var-point,i->coeff)).print(c);
+               ++i;
+       }
+
+       if (precedence() <= level)
+               c.s << ')';
+}
+
+void pseries::do_print(const print_context & c, unsigned level) const
+{
+       print_series(c, "", "", "*", "^", level);
+}
 
-               if (precedence() <= level)
-                       c.s << ")";
+void pseries::do_print_latex(const print_latex & c, unsigned level) const
+{
+       print_series(c, "{", "}", " ", "^", level);
+}
+
+void pseries::do_print_python(const print_python & c, unsigned level) const
+{
+       print_series(c, "", "", "*", "**", level);
+}
+
+void pseries::do_print_tree(const print_tree & c, unsigned level) const
+{
+       c.s << std::string(level, ' ') << class_name() << " @" << this
+           << std::hex << ", hash=0x" << hashvalue << ", flags=0x" << flags << std::dec
+           << std::endl;
+       size_t num = seq.size();
+       for (size_t i=0; i<num; ++i) {
+               seq[i].rest.print(c, level + c.delta_indent);
+               seq[i].coeff.print(c, level + c.delta_indent);
+               c.s << std::string(level + c.delta_indent, ' ') << "-----" << std::endl;
        }
+       var.print(c, level + c.delta_indent);
+       point.print(c, level + c.delta_indent);
+}
+
+void pseries::do_print_python_repr(const print_python_repr & c, unsigned level) const
+{
+       c.s << class_name() << "(relational(";
+       var.print(c);
+       c.s << ',';
+       point.print(c);
+       c.s << "),[";
+       size_t num = seq.size();
+       for (size_t i=0; i<num; ++i) {
+               if (i)
+                       c.s << ',';
+               c.s << '(';
+               seq[i].rest.print(c);
+               c.s << ',';
+               seq[i].coeff.print(c);
+               c.s << ')';
+       }
+       c.s << "])";
 }
 
 int pseries::compare_same_type(const basic & other) const
 {
-       GINAC_ASSERT(is_of_type(other, pseries));
+       GINAC_ASSERT(is_a<pseries>(other));
        const pseries &o = static_cast<const pseries &>(other);
        
        // first compare the lengths of the series...
@@ -240,22 +255,18 @@ int pseries::compare_same_type(const basic & other) const
 }
 
 /** Return the number of operands including a possible order term. */
-unsigned pseries::nops(void) const
+size_t pseries::nops() const
 {
        return seq.size();
 }
 
 /** Return the ith term in the series when represented as a sum. */
-ex pseries::op(int i) const
+ex pseries::op(size_t i) const
 {
-       if (i < 0 || unsigned(i) >= seq.size())
+       if (i >= seq.size())
                throw (std::out_of_range("op() out of range"));
-       return seq[i].rest * power(var - point, seq[i].coeff);
-}
 
-ex &pseries::let_op(int i)
-{
-       throw (std::logic_error("let_op not defined for pseries"));
+       return seq[i].rest * power(var - point, seq[i].coeff);
 }
 
 /** Return degree of highest power of the series.  This is usually the exponent
@@ -323,7 +334,7 @@ ex pseries::coeff(const ex &s, int n) const
 {
        if (var.is_equal(s)) {
                if (seq.empty())
-                       return _ex0();
+                       return _ex0;
                
                // Binary search in sequence for given power
                numeric looking_for = numeric(n);
@@ -345,7 +356,7 @@ ex pseries::coeff(const ex &s, int n) const
                                        throw(std::logic_error("pseries::coeff: compare() didn't return -1, 0 or 1"));
                        }
                }
-               return _ex0();
+               return _ex0;
        } else
                return convert_to_poly().coeff(s, n);
 }
@@ -396,13 +407,30 @@ ex pseries::evalf(int level) const
        return (new pseries(relational(var,point), new_seq))->setflag(status_flags::dynallocated | status_flags::evaluated);
 }
 
-ex pseries::subs(const lst & ls, const lst & lr, bool no_pattern) const
+ex pseries::conjugate() const
+{
+       epvector * newseq = conjugateepvector(seq);
+       ex newvar = var.conjugate();
+       ex newpoint = point.conjugate();
+
+       if (!newseq     && are_ex_trivially_equal(newvar, var) && are_ex_trivially_equal(point, newpoint)) {
+               return *this;
+       }
+
+       ex result = (new pseries(newvar==newpoint, newseq ? *newseq : seq))->setflag(status_flags::dynallocated);
+       if (newseq) {
+               delete newseq;
+       }
+       return result;
+}
+
+ex pseries::subs(const exmap & m, unsigned options) const
 {
        // If expansion variable is being substituted, convert the series to a
        // polynomial and do the substitution there because the result might
        // no longer be a power series
-       if (ls.has(var))
-               return convert_to_poly(true).subs(ls, lr, no_pattern);
+       if (m.find(var) != m.end())
+               return convert_to_poly(true).subs(m, options);
        
        // Otherwise construct a new series with substituted coefficients and
        // expansion point
@@ -410,10 +438,10 @@ ex pseries::subs(const lst & ls, const lst & lr, bool no_pattern) const
        newseq.reserve(seq.size());
        epvector::const_iterator it = seq.begin(), itend = seq.end();
        while (it != itend) {
-               newseq.push_back(expair(it->rest.subs(ls, lr, no_pattern), it->coeff));
+               newseq.push_back(expair(it->rest.subs(m, options), it->coeff));
                ++it;
        }
-       return (new pseries(relational(var,point.subs(ls, lr, no_pattern)), newseq))->setflag(status_flags::dynallocated);
+       return (new pseries(relational(var,point.subs(m, options)), newseq))->setflag(status_flags::dynallocated);
 }
 
 /** Implementation of ex::expand() for a power series.  It expands all the
@@ -432,14 +460,14 @@ ex pseries::expand(unsigned options) const
                ->setflag(status_flags::dynallocated | (options == 0 ? status_flags::expanded : 0));
 }
 
-/** Implementation of ex::diff() for a power series.  It treats the series as a
- *  polynomial.
+/** Implementation of ex::diff() for a power series.
  *  @see ex::diff */
 ex pseries::derivative(const symbol & s) const
 {
+       epvector new_seq;
+       epvector::const_iterator it = seq.begin(), itend = seq.end();
+
        if (s == var) {
-               epvector new_seq;
-               epvector::const_iterator it = seq.begin(), itend = seq.end();
                
                // FIXME: coeff might depend on var
                while (it != itend) {
@@ -452,10 +480,22 @@ ex pseries::derivative(const symbol & s) const
                        }
                        ++it;
                }
-               return pseries(relational(var,point), new_seq);
+
        } else {
-               return *this;
+
+               while (it != itend) {
+                       if (is_order_function(it->rest)) {
+                               new_seq.push_back(*it);
+                       } else {
+                               ex c = it->rest.diff(s);
+                               if (!c.is_zero())
+                                       new_seq.push_back(expair(c, it->coeff));
+                       }
+                       ++it;
+               }
        }
+
+       return pseries(relational(var,point), new_seq);
 }
 
 ex pseries::convert_to_poly(bool no_order) const
@@ -474,7 +514,7 @@ ex pseries::convert_to_poly(bool no_order) const
        return e;
 }
 
-bool pseries::is_terminating(void) const
+bool pseries::is_terminating() const
 {
        return seq.empty() || !is_order_function((seq.end()-1)->rest);
 }
@@ -489,31 +529,42 @@ bool pseries::is_terminating(void) const
 ex basic::series(const relational & r, int order, unsigned options) const
 {
        epvector seq;
-       numeric fac(1);
-       ex deriv = *this;
-       ex coeff = deriv.subs(r);
        const symbol &s = ex_to<symbol>(r.lhs());
-       
-       if (!coeff.is_zero())
-               seq.push_back(expair(coeff, _ex0()));
-       
+
+       // default for order-values that make no sense for Taylor expansion
+       if ((order <= 0) && this->has(s)) {
+               seq.push_back(expair(Order(_ex1), order));
+               return pseries(r, seq);
+       }
+
+       // do Taylor expansion
+       numeric fac = 1;
+       ex deriv = *this;
+       ex coeff = deriv.subs(r, subs_options::no_pattern);
+
+       if (!coeff.is_zero()) {
+               seq.push_back(expair(coeff, _ex0));
+       }
+
        int n;
        for (n=1; n<order; ++n) {
-               fac = fac.mul(numeric(n));
+               fac = fac.mul(n);
+               // We need to test for zero in order to see if the series terminates.
+               // The problem is that there is no such thing as a perfect test for
+               // zero.  Expanding the term occasionally helps a little...
                deriv = deriv.diff(s).expand();
-               if (deriv.is_zero()) {
-                       // Series terminates
+               if (deriv.is_zero())  // Series terminates
                        return pseries(r, seq);
-               }
-               coeff = deriv.subs(r);
+
+               coeff = deriv.subs(r, subs_options::no_pattern);
                if (!coeff.is_zero())
-                       seq.push_back(expair(fac.inverse() * coeff, numeric(n)));
+                       seq.push_back(expair(fac.inverse() * coeff, n));
        }
        
        // Higher-order terms, if present
        deriv = deriv.diff(s);
        if (!deriv.expand().is_zero())
-               seq.push_back(expair(Order(_ex1()), numeric(n)));
+               seq.push_back(expair(Order(_ex1), n));
        return pseries(r, seq);
 }
 
@@ -524,17 +575,17 @@ ex symbol::series(const relational & r, int order, unsigned options) const
 {
        epvector seq;
        const ex point = r.rhs();
-       GINAC_ASSERT(is_exactly_a<symbol>(r.lhs()));
+       GINAC_ASSERT(is_a<symbol>(r.lhs()));
 
        if (this->is_equal_same_type(ex_to<symbol>(r.lhs()))) {
                if (order > 0 && !point.is_zero())
-                       seq.push_back(expair(point, _ex0()));
+                       seq.push_back(expair(point, _ex0));
                if (order > 1)
-                       seq.push_back(expair(_ex1(), _ex1()));
+                       seq.push_back(expair(_ex1, _ex1));
                else
-                       seq.push_back(expair(Order(_ex1()), numeric(order)));
+                       seq.push_back(expair(Order(_ex1), numeric(order)));
        } else
-               seq.push_back(expair(*this, _ex0()));
+               seq.push_back(expair(*this, _ex0));
        return pseries(r, seq);
 }
 
@@ -550,7 +601,7 @@ ex pseries::add_series(const pseries &other) const
        // results in an empty (constant) series 
        if (!is_compatible_to(other)) {
                epvector nul;
-               nul.push_back(expair(Order(_ex1()), _ex0()));
+               nul.push_back(expair(Order(_ex1), _ex0));
                return pseries(relational(var,point), nul);
        }
        
@@ -598,7 +649,7 @@ ex pseries::add_series(const pseries &other) const
                } else {
                        // Add coefficient of a and b
                        if (is_order_function((*a).rest) || is_order_function((*b).rest)) {
-                               new_seq.push_back(expair(Order(_ex1()), (*a).coeff));
+                               new_seq.push_back(expair(Order(_ex1), (*a).coeff));
                                break;  // Order term ends the sequence
                        } else {
                                ex sum = (*a).rest + (*b).rest;
@@ -628,11 +679,11 @@ ex add::series(const relational & r, int order, unsigned options) const
        epvector::const_iterator itend = seq.end();
        for (; it!=itend; ++it) {
                ex op;
-               if (is_ex_exactly_of_type(it->rest, pseries))
+               if (is_exactly_a<pseries>(it->rest))
                        op = it->rest;
                else
                        op = it->rest.series(r, order, options);
-               if (!it->coeff.is_equal(_ex1()))
+               if (!it->coeff.is_equal(_ex1))
                        op = ex_to<pseries>(op).mul_const(ex_to<numeric>(it->coeff));
                
                // Series addition
@@ -675,7 +726,7 @@ ex pseries::mul_series(const pseries &other) const
        // results in an empty (constant) series 
        if (!is_compatible_to(other)) {
                epvector nul;
-               nul.push_back(expair(Order(_ex1()), _ex0()));
+               nul.push_back(expair(Order(_ex1), _ex0));
                return pseries(relational(var,point), nul);
        }
        
@@ -699,7 +750,7 @@ ex pseries::mul_series(const pseries &other) const
                cdeg_max = higher_order_c - 1;
        
        for (int cdeg=cdeg_min; cdeg<=cdeg_max; ++cdeg) {
-               ex co = _ex0();
+               ex co = _ex0;
                // c(i)=a(0)b(i)+...+a(i)b(0)
                for (int i=a_min; cdeg-i>=b_min; ++i) {
                        ex a_coeff = coeff(var, i);
@@ -711,7 +762,7 @@ ex pseries::mul_series(const pseries &other) const
                        new_seq.push_back(expair(co, numeric(cdeg)));
        }
        if (higher_order_c < INT_MAX)
-               new_seq.push_back(expair(Order(_ex1()), numeric(higher_order_c)));
+               new_seq.push_back(expair(Order(_ex1), numeric(higher_order_c)));
        return pseries(relational(var, point), new_seq);
 }
 
@@ -723,18 +774,65 @@ ex mul::series(const relational & r, int order, unsigned options) const
 {
        pseries acc; // Series accumulator
 
-       // Multiply with remaining terms
+       GINAC_ASSERT(is_a<symbol>(r.lhs()));
+       const ex& sym = r.lhs();
+               
+       // holds ldegrees of the series of individual factors
+       std::vector<int> ldegrees;
+
+       // find minimal degrees
        const epvector::const_iterator itbeg = seq.begin();
        const epvector::const_iterator itend = seq.end();
        for (epvector::const_iterator it=itbeg; it!=itend; ++it) {
-               ex op = recombine_pair_to_ex(*it).series(r, order, options);
+
+               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;
+               try {
+                       real_ldegree = buf.expand().ldegree(sym-r.rhs());
+               } catch (std::runtime_error) {}
+
+               if (real_ldegree == 0) {
+                       int orderloop = 0;
+                       do {
+                               orderloop++;
+                               real_ldegree = buf.series(r, orderloop, options).ldegree(sym);
+                       } while (real_ldegree == orderloop);
+               }
+
+               ldegrees.push_back(factor * real_ldegree);
+       }
+
+       int degsum = std::accumulate(ldegrees.begin(), ldegrees.end(), 0);
+
+       if (degsum >= order) {
+               epvector epv;
+               epv.push_back(expair(Order(_ex1), order));
+               return (new pseries(r, epv))->setflag(status_flags::dynallocated);
+       }
+
+       // Multiply with remaining terms
+       std::vector<int>::const_iterator itd = ldegrees.begin();
+       for (epvector::const_iterator it=itbeg; it!=itend; ++it, ++itd) {
+
+               // do series expansion with adjusted order
+               ex op = recombine_pair_to_ex(*it).series(r, order-degsum+(*itd), options);
 
                // Series multiplication
-               if (it==itbeg)
+               if (it == itbeg)
                        acc = ex_to<pseries>(op);
                else
                        acc = ex_to<pseries>(acc.mul_series(ex_to<pseries>(op)));
        }
+
        return acc.mul_const(ex_to<numeric>(overall_coeff));
 }
 
@@ -781,6 +879,9 @@ ex pseries::power_const(const numeric &p, int deg) const
        if (!(p*ldeg).is_integer())
                throw std::runtime_error("pseries::power_const(): trying to assemble a Puiseux series");
 
+       // adjust number of coefficients
+       deg = deg - (p*ldeg).to_int();
+       
        // O(x^n)^(-m) is undefined
        if (seq.size() == 1 && is_order_function(seq[0].rest) && p.real().is_negative())
                throw pole_error("pseries::power_const(): division by zero",1);
@@ -789,19 +890,16 @@ ex pseries::power_const(const numeric &p, int deg) const
        exvector co;
        co.reserve(deg);
        co.push_back(power(coeff(var, ldeg), p));
-       bool all_sums_zero = true;
        for (int i=1; i<deg; ++i) {
-               ex sum = _ex0();
+               ex sum = _ex0;
                for (int j=1; j<=i; ++j) {
                        ex c = coeff(var, j + ldeg);
                        if (is_order_function(c)) {
-                               co.push_back(Order(_ex1()));
+                               co.push_back(Order(_ex1));
                                break;
                        } else
                                sum += (p * j - (i - j)) * co[i - j] * c;
                }
-               if (!sum.is_zero())
-                       all_sums_zero = false;
                co.push_back(sum / coeff(var, ldeg) / i);
        }
        
@@ -816,8 +914,9 @@ ex pseries::power_const(const numeric &p, int deg) const
                        break;
                }
        }
-       if (!higher_order && !all_sums_zero)
-               new_seq.push_back(expair(Order(_ex1()), p * ldeg + deg));
+       if (!higher_order)
+               new_seq.push_back(expair(Order(_ex1), p * ldeg + deg));
+
        return pseries(relational(var,point), new_seq);
 }
 
@@ -841,38 +940,68 @@ pseries pseries::shift_exponents(int deg) const
 ex power::series(const relational & r, int order, unsigned options) const
 {
        // If basis is already a series, just power it
-       if (is_ex_exactly_of_type(basis, pseries))
+       if (is_exactly_a<pseries>(basis))
                return ex_to<pseries>(basis).power_const(ex_to<numeric>(exponent), order);
 
        // Basis is not a series, may there be a singularity?
        bool must_expand_basis = false;
        try {
-               basis.subs(r);
+               basis.subs(r, subs_options::no_pattern);
        } catch (pole_error) {
                must_expand_basis = true;
        }
-               
+
        // Is the expression of type something^(-int)?
-       if (!must_expand_basis && !exponent.info(info_flags::negint))
+       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).is_zero())
+       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));
+                       new_seq.push_back(expair(_ex1, exponent));
                else
-                       new_seq.push_back(expair(Order(_ex1()), exponent));
+                       new_seq.push_back(expair(Order(_ex1), exponent));
                return pseries(r, new_seq);
        }
 
        // No, expand basis into series
-       ex e = basis.series(r, order, options);
-       return ex_to<pseries>(e).power_const(ex_to<numeric>(exponent), order);
+
+       numeric numexp;
+       if (is_a<numeric>(exponent)) {
+               numexp = ex_to<numeric>(exponent);
+       } else {
+               numexp = 0;
+       }
+       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);
+       
+       ex result;
+       try {
+               result = ex_to<pseries>(e).power_const(numexp, order);
+       } catch (pole_error) {
+               epvector ser;
+               ser.push_back(expair(Order(_ex1), order));
+               result = pseries(r, ser);
+       }
+
+       return result;
 }
 
 
@@ -880,7 +1009,7 @@ ex power::series(const relational & r, int order, unsigned options) const
 ex pseries::series(const relational & r, int order, unsigned options) const
 {
        const ex p = r.rhs();
-       GINAC_ASSERT(is_exactly_a<symbol>(r.lhs()));
+       GINAC_ASSERT(is_a<symbol>(r.lhs()));
        const symbol &s = ex_to<symbol>(r.lhs());
        
        if (var.is_equal(s) && point.is_equal(p)) {
@@ -892,7 +1021,7 @@ ex pseries::series(const relational & r, int order, unsigned options) const
                        while (it != itend) {
                                int o = ex_to<numeric>(it->coeff).to_int();
                                if (o >= order) {
-                                       new_seq.push_back(expair(Order(_ex1()), o));
+                                       new_seq.push_back(expair(Order(_ex1), o));
                                        break;
                                }
                                new_seq.push_back(*it);
@@ -916,14 +1045,13 @@ ex pseries::series(const relational & r, int order, unsigned options) const
  *  @return an expression holding a pseries object */
 ex ex::series(const ex & r, int order, unsigned options) const
 {
-       GINAC_ASSERT(bp!=0);
        ex e;
        relational rel_;
        
-       if (is_ex_exactly_of_type(r,relational))
+       if (is_a<relational>(r))
                rel_ = ex_to<relational>(r);
-       else if (is_ex_exactly_of_type(r,symbol))
-               rel_ = relational(r,_ex0());
+       else if (is_a<symbol>(r))
+               rel_ = relational(r,_ex0);
        else
                throw (std::logic_error("ex::series(): expansion point has unknown type"));