]> www.ginac.de Git - ginac.git/blobdiff - ginac/pseries.cpp
subs() and normal() use maps instead of lists, resulting in a huge performance
[ginac.git] / ginac / pseries.cpp
index 9d04f6a996346d42e5d60dd603702105a9b9867b..22d7b7777a19c8c5ea82eec48b2b99adfc707f2a 100644 (file)
@@ -4,7 +4,7 @@
  *  methods for series expansion. */
 
 /*
- *  GiNaC Copyright (C) 1999-2001 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2003 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
  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
+#include <iostream>
 #include <stdexcept>
 
 #include "pseries.h"
 #include "add.h"
-#include "inifcns.h"
+#include "inifcns.h" // for Order function
 #include "lst.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 {
 
@@ -42,23 +43,10 @@ GINAC_IMPLEMENT_REGISTERED_CLASS(pseries, basic)
 
 
 /*
- *  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 +56,7 @@ 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)
@@ -76,11 +64,10 @@ 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_ex_exactly_of_type(rel_, relational));
-       GINAC_ASSERT(is_ex_exactly_of_type(rel_.lhs(),symbol));
+       GINAC_ASSERT(is_a<relational>(rel_));
+       GINAC_ASSERT(is_a<symbol>(rel_.lhs()));
        point = rel_.rhs();
-       var = *static_cast<symbol *>(rel_.lhs().bp);
+       var = rel_.lhs();
 }
 
 
@@ -88,9 +75,8 @@ 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;
@@ -119,20 +105,19 @@ void pseries::archive(archive_node &n) const
 DEFAULT_UNARCHIVE(pseries)
 
 //////////
-// functions overriding virtual functions from bases classes
+// functions overriding virtual functions from base classes
 //////////
 
 void pseries::print(const print_context & c, unsigned level) const
 {
-       debugmsg("pseries print", LOGLEVEL_PRINT);
-
-       if (is_of_type(c, print_tree)) {
+       if (is_a<print_tree>(c)) {
 
                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;
-               for (unsigned i=0; i<seq.size(); ++i) {
+               size_t num = seq.size();
+               for (size_t 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;
@@ -140,19 +125,37 @@ void pseries::print(const print_context & c, unsigned level) const
                var.print(c, level + delta_indent);
                point.print(c, level + delta_indent);
 
+       } else if (is_a<print_python_repr>(c)) {
+               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 << "])";
        } else {
 
                if (precedence() <= level)
                        c.s << "(";
                
-               std::string par_open = is_of_type(c, print_latex) ? "{(" : "(";
-               std::string par_close = is_of_type(c, print_latex) ? ")}" : ")";
+               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.size() == 0)
+               if (seq.empty())
                        c.s << '0';
-               for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
+               epvector::const_iterator i = seq.begin(), end = seq.end();
+               while (i != end) {
                        // print a sign, if needed
                        if (i != seq.begin())
                                c.s << '+';
@@ -168,7 +171,7 @@ void pseries::print(const print_context & c, unsigned level) const
                                }
                                // print 'coeff', something like (x-1)^42
                                if (!i->coeff.is_zero()) {
-                                       if (is_of_type(c, print_latex))
+                                       if (is_a<print_latex>(c))
                                                c.s << ' ';
                                        else
                                                c.s << '*';
@@ -178,14 +181,17 @@ void pseries::print(const print_context & c, unsigned level) const
                                                c.s << par_close;
                                        } else
                                                var.print(c);
-                                       if (i->coeff.compare(_ex1())) {
-                                               c.s << '^';
+                                       if (i->coeff.compare(_ex1)) {
+                                               if (is_a<print_python>(c))
+                                                       c.s << "**";
+                                               else
+                                                       c.s << '^';
                                                if (i->coeff.info(info_flags::negative)) {
                                                        c.s << par_open;
                                                        i->coeff.print(c);
                                                        c.s << par_close;
                                                } else {
-                                                       if (is_of_type(c, print_latex)) {
+                                                       if (is_a<print_latex>(c)) {
                                                                c.s << '{';
                                                                i->coeff.print(c);
                                                                c.s << '}';
@@ -196,6 +202,7 @@ void pseries::print(const print_context & c, unsigned level) const
                                }
                        } else
                                Order(power(var-point,i->coeff)).print(c);
+                       ++i;
                }
 
                if (precedence() <= level)
@@ -205,7 +212,7 @@ void pseries::print(const print_context & c, unsigned level) const
 
 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...
@@ -237,22 +244,18 @@ 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
@@ -263,7 +266,7 @@ int pseries::degree(const ex &s) const
        if (var.is_equal(s)) {
                // Return last exponent
                if (seq.size())
-                       return ex_to_numeric((*(seq.end() - 1)).coeff).to_int();
+                       return ex_to<numeric>((seq.end()-1)->coeff).to_int();
                else
                        return 0;
        } else {
@@ -291,7 +294,7 @@ int pseries::ldegree(const ex &s) const
        if (var.is_equal(s)) {
                // Return first exponent
                if (seq.size())
-                       return ex_to_numeric((*(seq.begin())).coeff).to_int();
+                       return ex_to<numeric>((seq.begin())->coeff).to_int();
                else
                        return 0;
        } else {
@@ -319,16 +322,16 @@ int pseries::ldegree(const ex &s) const
 ex pseries::coeff(const ex &s, int n) const
 {
        if (var.is_equal(s)) {
-               if (seq.size() == 0)
-                       return _ex0();
+               if (seq.empty())
+                       return _ex0;
                
                // Binary search in sequence for given power
                numeric looking_for = numeric(n);
                int lo = 0, hi = seq.size() - 1;
                while (lo <= hi) {
                        int mid = (lo + hi) / 2;
-                       GINAC_ASSERT(is_ex_exactly_of_type(seq[mid].coeff, numeric));
-                       int cmp = ex_to_numeric(seq[mid].coeff).compare(looking_for);
+                       GINAC_ASSERT(is_exactly_a<numeric>(seq[mid].coeff));
+                       int cmp = ex_to<numeric>(seq[mid].coeff).compare(looking_for);
                        switch (cmp) {
                                case -1:
                                        lo = mid + 1;
@@ -342,7 +345,7 @@ 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);
 }
@@ -353,7 +356,7 @@ ex pseries::collect(const ex &s, bool distributed) const
        return *this;
 }
 
-/** Evaluate coefficients. */
+/** Perform coefficient-wise automatic term rewriting rules in this class. */
 ex pseries::eval(int level) const
 {
        if (level == 1)
@@ -393,13 +396,13 @@ 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) const
+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);
+       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
@@ -407,10 +410,10 @@ ex pseries::subs(const lst & ls, const lst & lr) 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), it->coeff));
+               newseq.push_back(expair(it->rest.subs(m, options), it->coeff));
                ++it;
        }
-       return (new pseries(relational(var,point.subs(ls, lr)), 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
@@ -418,23 +421,25 @@ ex pseries::subs(const lst & ls, const lst & lr) const
 ex pseries::expand(unsigned options) const
 {
        epvector newseq;
-       for (epvector::const_iterator i=seq.begin(); i!=seq.end(); ++i) {
+       epvector::const_iterator i = seq.begin(), end = seq.end();
+       while (i != end) {
                ex restexp = i->rest.expand();
                if (!restexp.is_zero())
                        newseq.push_back(expair(restexp, i->coeff));
+               ++i;
        }
        return (new pseries(relational(var,point), newseq))
-               ->setflag(status_flags::dynallocated | status_flags::expanded);
+               ->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) {
@@ -447,10 +452,22 @@ 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
@@ -469,9 +486,9 @@ ex pseries::convert_to_poly(bool no_order) const
        return e;
 }
 
-bool pseries::is_terminating(void) const
+bool pseries::is_terminating() const
 {
-       return seq.size() == 0 || !is_order_function((seq.end()-1)->rest);
+       return seq.empty() || !is_order_function((seq.end()-1)->rest);
 }
 
 
@@ -484,31 +501,33 @@ bool pseries::is_terminating(void) const
 ex basic::series(const relational & r, int order, unsigned options) const
 {
        epvector seq;
-       numeric fac(1);
+       numeric fac = 1;
        ex deriv = *this;
        ex coeff = deriv.subs(r);
-       const symbol &s = static_cast<symbol &>(*r.lhs().bp);
+       const symbol &s = ex_to<symbol>(r.lhs());
        
        if (!coeff.is_zero())
-               seq.push_back(expair(coeff, _ex0()));
+               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);
                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);
 }
 
@@ -519,18 +538,17 @@ ex symbol::series(const relational & r, int order, unsigned options) const
 {
        epvector seq;
        const ex point = r.rhs();
-       GINAC_ASSERT(is_ex_exactly_of_type(r.lhs(),symbol));
-       ex s = r.lhs();
-       
-       if (this->is_equal(*s.bp)) {
+       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);
 }
 
@@ -546,7 +564,7 @@ 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);
        }
        
@@ -566,7 +584,7 @@ ex pseries::add_series(const pseries &other) const
                        }
                        break;
                } else
-                       pow_a = ex_to_numeric((*a).coeff).to_int();
+                       pow_a = ex_to<numeric>((*a).coeff).to_int();
                
                // If b is empty, fill up with elements from a and stop
                if (b == b_end) {
@@ -576,7 +594,7 @@ ex pseries::add_series(const pseries &other) const
                        }
                        break;
                } else
-                       pow_b = ex_to_numeric((*b).coeff).to_int();
+                       pow_b = ex_to<numeric>((*b).coeff).to_int();
                
                // a and b are non-empty, compare powers
                if (pow_a < pow_b) {
@@ -594,7 +612,7 @@ 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;
@@ -624,15 +642,15 @@ 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()))
-                       op = ex_to_pseries(op).mul_const(ex_to_numeric(it->coeff));
+               if (!it->coeff.is_equal(_ex1))
+                       op = ex_to<pseries>(op).mul_const(ex_to<numeric>(it->coeff));
                
                // Series addition
-               acc = ex_to_pseries(acc).add_series(ex_to_pseries(op));
+               acc = ex_to<pseries>(acc).add_series(ex_to<pseries>(op));
        }
        return acc;
 }
@@ -671,13 +689,12 @@ 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);
        }
        
        // Series multiplication
        epvector new_seq;
-       
        int a_max = degree(var);
        int b_max = other.degree(var);
        int a_min = ldegree(var);
@@ -696,7 +713,7 @@ 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);
@@ -708,7 +725,7 @@ 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);
 }
 
@@ -718,30 +735,21 @@ ex pseries::mul_series(const pseries &other) const
  *  @see ex::series */
 ex mul::series(const relational & r, int order, unsigned options) const
 {
-       ex acc; // Series accumulator
-       
-       // Get first term from overall_coeff
-       acc = overall_coeff.series(r, order, options);
-       
+       pseries acc; // Series accumulator
+
        // Multiply with remaining terms
-       epvector::const_iterator it = seq.begin();
-       epvector::const_iterator itend = seq.end();
-       for (; it!=itend; ++it) {
-               ex op = it->rest;
-               if (op.info(info_flags::numeric)) {
-                       // series * const (special case, faster)
-                       ex f = power(op, it->coeff);
-                       acc = ex_to_pseries(acc).mul_const(ex_to_numeric(f));
-                       continue;
-               } else if (!is_ex_exactly_of_type(op, pseries))
-                       op = op.series(r, order, options);
-               if (!it->coeff.is_equal(_ex1()))
-                       op = ex_to_pseries(op).power_const(ex_to_numeric(it->coeff), order);
+       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);
 
                // Series multiplication
-               acc = ex_to_pseries(acc).mul_series(ex_to_pseries(op));
+               if (it==itbeg)
+                       acc = ex_to<pseries>(op);
+               else
+                       acc = ex_to<pseries>(acc.mul_series(ex_to<pseries>(op)));
        }
-       return acc;
+       return acc.mul_const(ex_to<numeric>(overall_coeff));
 }
 
 
@@ -752,6 +760,7 @@ ex mul::series(const relational & r, int order, unsigned options) const
 ex pseries::power_const(const numeric &p, int deg) const
 {
        // method:
+       // (due to Leonhard Euler)
        // let A(x) be this series and for the time being let it start with a
        // constant (later we'll generalize):
        //     A(x) = a_0 + a_1*x + a_2*x^2 + ...
@@ -771,18 +780,24 @@ ex pseries::power_const(const numeric &p, int deg) const
        // repeat the above derivation.  The leading power of C2(x) = A2(x)^2 is
        // then of course x^(p*m) but the recurrence formula still holds.
        
-       if (seq.size()==0) {
-               // as a spacial case, handle the empty (zero) series honoring the
+       if (seq.empty()) {
+               // as a special case, handle the empty (zero) series honoring the
                // usual power laws such as implemented in power::eval()
                if (p.real().is_zero())
-                       throw (std::domain_error("pseries::power_const(): pow(0,I) is undefined"));
+                       throw std::domain_error("pseries::power_const(): pow(0,I) is undefined");
                else if (p.real().is_negative())
-                       throw (pole_error("pseries::power_const(): division by zero",1));
+                       throw pole_error("pseries::power_const(): division by zero",1);
                else
                        return *this;
        }
        
-       int ldeg = ldegree(var);
+       const int ldeg = ldegree(var);
+       if (!(p*ldeg).is_integer())
+               throw std::runtime_error("pseries::power_const(): trying to assemble a Puiseux series");
+
+       // 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);
        
        // Compute coefficients of the powered series
        exvector co;
@@ -790,18 +805,18 @@ ex pseries::power_const(const numeric &p, int deg) const
        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) / numeric(i));
+               co.push_back(sum / coeff(var, ldeg) / i);
        }
        
        // Construct new series (of non-zero coefficients)
@@ -809,14 +824,14 @@ ex pseries::power_const(const numeric &p, int deg) const
        bool higher_order = false;
        for (int i=0; i<deg; ++i) {
                if (!co[i].is_zero())
-                       new_seq.push_back(expair(co[i], numeric(i) + p * ldeg));
+                       new_seq.push_back(expair(co[i], p * ldeg + i));
                if (is_order_function(co[i])) {
                        higher_order = true;
                        break;
                }
        }
        if (!higher_order && !all_sums_zero)
-               new_seq.push_back(expair(Order(_ex1()), numeric(deg) + p * ldeg));
+               new_seq.push_back(expair(Order(_ex1), p * ldeg + deg));
        return pseries(relational(var,point), new_seq);
 }
 
@@ -824,9 +839,12 @@ ex pseries::power_const(const numeric &p, int deg) const
 /** Return a new pseries object with the powers shifted by deg. */
 pseries pseries::shift_exponents(int deg) const
 {
-       epvector newseq(seq);
-       for (epvector::iterator i=newseq.begin(); i!=newseq.end(); ++i)
-               i->coeff = i->coeff + deg;
+       epvector newseq = seq;
+       epvector::iterator i = newseq.begin(), end  = newseq.end();
+       while (i != end) {
+               i->coeff += deg;
+               ++i;
+       }
        return pseries(relational(var, point), newseq);
 }
 
@@ -836,33 +854,39 @@ pseries pseries::shift_exponents(int deg) const
  *  @see ex::series */
 ex power::series(const relational & r, int order, unsigned options) const
 {
-       ex e;
-       if (!is_ex_exactly_of_type(basis, pseries)) {
-               // Basis is not a series, may there be a singularity?
-               bool must_expand_basis = false;
-               try {
-                       basis.subs(r);
-               } catch (pole_error) {
-                       must_expand_basis = true;
-               }
-               
-               // Is the expression of type something^(-int)?
-               if (!must_expand_basis && !exponent.info(info_flags::negint))
-                       return basic::series(r, order, options);
+       // If basis is already a series, just power it
+       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);
+       } catch (pole_error) {
+               must_expand_basis = true;
+       }
                
-               // Is the expression of type 0^something?
-               if (!must_expand_basis && !basis.subs(r).is_zero())
-                       return basic::series(r, order, options);
+       // Is the expression of type something^(-int)?
+       if (!must_expand_basis && !exponent.info(info_flags::negint))
+               return basic::series(r, order, options);
                
-               // Singularity encountered, expand basis into series
-               e = basis.series(r, order, options);
-       } else {
-               // Basis is a series
-               e = basis;
+       // Is the expression of type 0^something?
+       if (!must_expand_basis && !basis.subs(r).is_zero())
+               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);
        }
-       
-       // Power e
-       return ex_to_pseries(e).power_const(ex_to_numeric(exponent), order);
+
+       // No, expand basis into series
+       ex e = basis.series(r, order, options);
+       return ex_to<pseries>(e).power_const(ex_to<numeric>(exponent), order);
 }
 
 
@@ -870,8 +894,8 @@ 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_ex_exactly_of_type(r.lhs(),symbol));
-       const symbol &s = static_cast<symbol &>(*r.lhs().bp);
+       GINAC_ASSERT(is_a<symbol>(r.lhs()));
+       const symbol &s = ex_to<symbol>(r.lhs());
        
        if (var.is_equal(s) && point.is_equal(p)) {
                if (order > degree(s))
@@ -880,9 +904,9 @@ ex pseries::series(const relational & r, int order, unsigned options) const
                        epvector new_seq;
                        epvector::const_iterator it = seq.begin(), itend = seq.end();
                        while (it != itend) {
-                               int o = ex_to_numeric(it->coeff).to_int();
+                               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);
@@ -906,14 +930,13 @@ 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))
-               rel_ = ex_to_relational(r);
-       else if (is_ex_exactly_of_type(r,symbol))
-               rel_ = relational(r,_ex0());
+       if (is_a<relational>(r))
+               rel_ = ex_to<relational>(r);
+       else if (is_a<symbol>(r))
+               rel_ = relational(r,_ex0);
        else
                throw (std::logic_error("ex::series(): expansion point has unknown type"));