]> www.ginac.de Git - ginac.git/blobdiff - ginac/power.cpp
- input parser recognizes "sqrt()", which is also used in the output
[ginac.git] / ginac / power.cpp
index 1fe5063c222ab91adaee973323a481593d32a771..78c9c9696d14303b468a4f3b1c69b460560a314a 100644 (file)
@@ -36,7 +36,6 @@
 #include "symbol.h"
 #include "print.h"
 #include "archive.h"
-#include "debugmsg.h"
 #include "utils.h"
 
 namespace GiNaC {
@@ -46,13 +45,10 @@ GINAC_IMPLEMENT_REGISTERED_CLASS(power, basic)
 typedef std::vector<int> intvector;
 
 //////////
-// default ctor, dtor, copy ctor assignment operator and helpers
+// default ctor, dtor, copy ctor, assignment operator and helpers
 //////////
 
-power::power() : inherited(TINFO_power)
-{
-       debugmsg("power default ctor",LOGLEVEL_CONSTRUCT);
-}
+power::power() : inherited(TINFO_power) { }
 
 void power::copy(const power & other)
 {
@@ -67,17 +63,7 @@ DEFAULT_DESTROY(power)
 // other ctors
 //////////
 
-power::power(const ex & lh, const ex & rh) : inherited(TINFO_power), basis(lh), exponent(rh)
-{
-       debugmsg("power ctor from ex,ex",LOGLEVEL_CONSTRUCT);
-}
-
-/** Ctor from an ex and a bare numeric.  This is somewhat more efficient than
- *  the normal ctor from two ex whenever it can be used. */
-power::power(const ex & lh, const numeric & rh) : inherited(TINFO_power), basis(lh), exponent(rh)
-{
-       debugmsg("power ctor from ex,numeric",LOGLEVEL_CONSTRUCT);
-}
+// all inlined
 
 //////////
 // archiving
@@ -85,7 +71,6 @@ power::power(const ex & lh, const numeric & rh) : inherited(TINFO_power), basis(
 
 power::power(const archive_node &n, const lst &sym_lst) : inherited(n, sym_lst)
 {
-       debugmsg("power ctor from archive_node", LOGLEVEL_CONSTRUCT);
        n.find_ex("basis", basis, sym_lst);
        n.find_ex("exponent", exponent, sym_lst);
 }
@@ -100,7 +85,7 @@ void power::archive(archive_node &n) const
 DEFAULT_UNARCHIVE(power)
 
 //////////
-// functions overriding virtual functions from bases classes
+// functions overriding virtual functions from base classes
 //////////
 
 // public
@@ -109,7 +94,7 @@ static void print_sym_pow(const print_context & c, const symbol &x, int exp)
 {
        // Optimal output of integer powers of symbols to aid compiler CSE.
        // C.f. ISO/IEC 14882:1998, section 1.9 [intro execution], paragraph 15
-       // to learn why such a hack is really necessary.
+       // to learn why such a parenthisation is really necessary.
        if (exp == 1) {
                x.print(c);
        } else if (exp == 2) {
@@ -131,8 +116,6 @@ static void print_sym_pow(const print_context & c, const symbol &x, int exp)
 
 void power::print(const print_context & c, unsigned level) const
 {
-       debugmsg("power print", LOGLEVEL_PRINT);
-
        if (is_a<print_tree>(c)) {
 
                inherited::print(c, level);
@@ -156,7 +139,7 @@ void power::print(const print_context & c, unsigned level) const
                        c.s << ')';
 
                // <expr>^-1 is printed as "1.0/<expr>" or with the recip() function of CLN
-               } else if (exponent.compare(_num_1()) == 0) {
+               } else if (exponent.compare(_num_1) == 0) {
                        if (is_a<print_csrc_cl_N>(c))
                                c.s << "recip(";
                        else
@@ -178,7 +161,7 @@ void power::print(const print_context & c, unsigned level) const
 
        } else {
 
-               if (exponent.is_equal(_ex1_2())) {
+               if (exponent.is_equal(_ex1_2)) {
                        if (is_a<print_latex>(c))
                                c.s << "\\sqrt{";
                        else
@@ -250,30 +233,28 @@ ex power::map(map_function & f) const
 
 int power::degree(const ex & s) const
 {
-       if (is_exactly_of_type(*exponent.bp,numeric)) {
-               if (basis.is_equal(s)) {
-                       if (ex_to<numeric>(exponent).is_integer())
-                               return ex_to<numeric>(exponent).to_int();
-                       else
-                               return 0;
-               } else
+       if (is_ex_exactly_of_type(exponent, numeric) && ex_to<numeric>(exponent).is_integer()) {
+               if (basis.is_equal(s))
+                       return ex_to<numeric>(exponent).to_int();
+               else
                        return basis.degree(s) * ex_to<numeric>(exponent).to_int();
-       }
-       return 0;
+       } else if (basis.has(s))
+               throw(std::runtime_error("power::degree(): undefined degree because of non-integer exponent"));
+       else
+               return 0;
 }
 
 int power::ldegree(const ex & s) const 
 {
-       if (is_exactly_of_type(*exponent.bp,numeric)) {
-               if (basis.is_equal(s)) {
-                       if (ex_to<numeric>(exponent).is_integer())
-                               return ex_to<numeric>(exponent).to_int();
-                       else
-                               return 0;
-               } else
+       if (is_ex_exactly_of_type(exponent, numeric) && ex_to<numeric>(exponent).is_integer()) {
+               if (basis.is_equal(s))
+                       return ex_to<numeric>(exponent).to_int();
+               else
                        return basis.ldegree(s) * ex_to<numeric>(exponent).to_int();
-       }
-       return 0;
+       } else if (basis.has(s))
+               throw(std::runtime_error("power::ldegree(): undefined degree because of non-integer exponent"));
+       else
+               return 0;
 }
 
 ex power::coeff(const ex & s, int n) const
@@ -283,40 +264,42 @@ ex power::coeff(const ex & s, int n) const
                if (n == 0)
                        return *this;
                else
-                       return _ex0();
+                       return _ex0;
        } else {
                // basis equal to s
-               if (is_exactly_of_type(*exponent.bp, numeric) && ex_to<numeric>(exponent).is_integer()) {
+               if (is_ex_exactly_of_type(exponent, numeric) && ex_to<numeric>(exponent).is_integer()) {
                        // integer exponent
                        int int_exp = ex_to<numeric>(exponent).to_int();
                        if (n == int_exp)
-                               return _ex1();
+                               return _ex1;
                        else
-                               return _ex0();
+                               return _ex0;
                } else {
                        // non-integer exponents are treated as zero
                        if (n == 0)
                                return *this;
                        else
-                               return _ex0();
+                               return _ex0;
                }
        }
 }
 
+/** Perform automatic term rewriting rules in this class.  In the following
+ *  x, x1, x2,... stand for a symbolic variables of type ex and c, c1, c2...
+ *  stand for such expressions that contain a plain number.
+ *  - ^(x,0) -> 1  (also handles ^(0,0))
+ *  - ^(x,1) -> x
+ *  - ^(0,c) -> 0 or exception  (depending on the real part of c)
+ *  - ^(1,x) -> 1
+ *  - ^(c1,c2) -> *(c1^n,c1^(c2-n))  (so that 0<(c2-n)<1, try to evaluate roots, possibly in numerator and denominator of c1)
+ *  - ^(^(x,c1),c2) -> ^(x,c1*c2)  (c2 integer or -1 < c1 <= 1, case c1=1 should not happen, see below!)
+ *  - ^(*(x,y,z),c) -> *(x^c,y^c,z^c)  (if c integer)
+ *  - ^(*(x,c1),c2) -> ^(x,c2)*c1^c2  (c1>0)
+ *  - ^(*(x,c1),c2) -> ^(-x,c2)*c1^c2  (c1<0)
+ *
+ *  @param level cut-off in recursive evaluation */
 ex power::eval(int level) const
 {
-       // simplifications: ^(x,0) -> 1 (0^0 handled here)
-       //                  ^(x,1) -> x
-       //                  ^(0,c1) -> 0 or exception (depending on real value of c1)
-       //                  ^(1,x) -> 1
-       //                  ^(c1,c2) -> *(c1^n,c1^(c2-n)) (c1, c2 numeric(), 0<(c2-n)<1 except if c1,c2 are rational, but c1^c2 is not)
-       //                  ^(^(x,c1),c2) -> ^(x,c1*c2) (c1, c2 numeric(), c2 integer or -1 < c1 <= 1, case c1=1 should not happen, see below!)
-       //                  ^(*(x,y,z),c1) -> *(x^c1,y^c1,z^c1) (c1 integer)
-       //                  ^(*(x,c1),c2) -> ^(x,c2)*c1^c2 (c1, c2 numeric(), c1>0)
-       //                  ^(*(x,c1),c2) -> ^(-x,c2)*c1^c2 (c1, c2 numeric(), c1<0)
-       
-       debugmsg("power eval",LOGLEVEL_MEMBER_FUNCTION);
-       
        if ((level==1) && (flags & status_flags::evaluated))
                return *this;
        else if (level == -max_recursion_level)
@@ -327,77 +310,97 @@ ex power::eval(int level) const
        
        bool basis_is_numerical = false;
        bool exponent_is_numerical = false;
-       numeric * num_basis;
-       numeric * num_exponent;
+       const numeric *num_basis;
+       const numeric *num_exponent;
        
-       if (is_exactly_of_type(*ebasis.bp,numeric)) {
+       if (is_ex_exactly_of_type(ebasis, numeric)) {
                basis_is_numerical = true;
-               num_basis = static_cast<numeric *>(ebasis.bp);
+               num_basis = &ex_to<numeric>(ebasis);
        }
-       if (is_exactly_of_type(*eexponent.bp,numeric)) {
+       if (is_ex_exactly_of_type(eexponent, numeric)) {
                exponent_is_numerical = true;
-               num_exponent = static_cast<numeric *>(eexponent.bp);
+               num_exponent = &ex_to<numeric>(eexponent);
        }
        
-       // ^(x,0) -> 1 (0^0 also handled here)
+       // ^(x,0) -> 1  (0^0 also handled here)
        if (eexponent.is_zero()) {
                if (ebasis.is_zero())
                        throw (std::domain_error("power::eval(): pow(0,0) is undefined"));
                else
-                       return _ex1();
+                       return _ex1;
        }
        
        // ^(x,1) -> x
-       if (eexponent.is_equal(_ex1()))
+       if (eexponent.is_equal(_ex1))
                return ebasis;
-       
-       // ^(0,c1) -> 0 or exception (depending on real value of c1)
+
+       // ^(0,c1) -> 0 or exception  (depending on real value of c1)
        if (ebasis.is_zero() && exponent_is_numerical) {
                if ((num_exponent->real()).is_zero())
                        throw (std::domain_error("power::eval(): pow(0,I) is undefined"));
                else if ((num_exponent->real()).is_negative())
                        throw (pole_error("power::eval(): division by zero",1));
                else
-                       return _ex0();
+                       return _ex0;
        }
-       
+
        // ^(1,x) -> 1
-       if (ebasis.is_equal(_ex1()))
-               return _ex1();
-       
+       if (ebasis.is_equal(_ex1))
+               return _ex1;
+
        if (exponent_is_numerical) {
 
-               // ^(c1,c2) -> c1^c2 (c1, c2 numeric(),
+               // ^(c1,c2) -> c1^c2  (c1, c2 numeric(),
                // except if c1,c2 are rational, but c1^c2 is not)
                if (basis_is_numerical) {
-                       bool basis_is_crational = num_basis->is_crational();
-                       bool exponent_is_crational = num_exponent->is_crational();
-                       numeric res = num_basis->power(*num_exponent);
-               
-                       if ((!basis_is_crational || !exponent_is_crational)
-                               || res.is_crational()) {
+                       const bool basis_is_crational = num_basis->is_crational();
+                       const bool exponent_is_crational = num_exponent->is_crational();
+                       if (!basis_is_crational || !exponent_is_crational) {
+                               // return a plain float
+                               return (new numeric(num_basis->power(*num_exponent)))->setflag(status_flags::dynallocated |
+                                                                                              status_flags::evaluated |
+                                                                                              status_flags::expanded);
+                       }
+
+                       const numeric res = num_basis->power(*num_exponent);
+                       if (res.is_crational()) {
                                return res;
                        }
                        GINAC_ASSERT(!num_exponent->is_integer());  // has been handled by now
 
-                       // ^(c1,n/m) -> *(c1^q,c1^(n/m-q)), 0<(n/m-h)<1, q integer
+                       // ^(c1,n/m) -> *(c1^q,c1^(n/m-q)), 0<(n/m-q)<1, q integer
                        if (basis_is_crational && exponent_is_crational
-                               && num_exponent->is_real()
-                               && !num_exponent->is_integer()) {
-                               numeric n = num_exponent->numer();
-                               numeric m = num_exponent->denom();
+                           && num_exponent->is_real()
+                           && !num_exponent->is_integer()) {
+                               const numeric n = num_exponent->numer();
+                               const numeric m = num_exponent->denom();
                                numeric r;
                                numeric q = iquo(n, m, r);
                                if (r.is_negative()) {
-                                       r = r.add(m);
-                                       q = q.sub(_num1());
+                                       r += m;
+                                       --q;
                                }
-                               if (q.is_zero())  // the exponent was in the allowed range 0<(n/m)<1
+                               if (q.is_zero()) {  // the exponent was in the allowed range 0<(n/m)<1
+                                       if (num_basis->is_rational() && !num_basis->is_integer()) {
+                                               // try it for numerator and denominator separately, in order to
+                                               // partially simplify things like (5/8)^(1/3) -> 1/2*5^(1/3)
+                                               const numeric bnum = num_basis->numer();
+                                               const numeric bden = num_basis->denom();
+                                               const numeric res_bnum = bnum.power(*num_exponent);
+                                               const numeric res_bden = bden.power(*num_exponent);
+                                               if (res_bnum.is_integer())
+                                                       return (new mul(power(bden,-*num_exponent),res_bnum))->setflag(status_flags::dynallocated | status_flags::evaluated);
+                                               if (res_bden.is_integer())
+                                                       return (new mul(power(bnum,*num_exponent),res_bden.inverse()))->setflag(status_flags::dynallocated | status_flags::evaluated);
+                                       }
                                        return this->hold();
-                               else {
-                                       epvector res;
-                                       res.push_back(expair(ebasis,r.div(m)));
-                                       return (new mul(res,ex(num_basis->power_dyn(q))))->setflag(status_flags::dynallocated | status_flags::evaluated);
+                               } else {
+                                       // assemble resulting product, but allowing for a re-evaluation,
+                                       // because otherwise we'll end up with something like
+                                       //    (7/8)^(4/3)  ->  7/8*(1/2*7^(1/3))
+                                       // instead of 7/16*7^(1/3).
+                                       ex prod = power(*num_basis,r.div(m));
+                                       return prod*power(*num_basis,q);
                                }
                        }
                }
@@ -412,7 +415,7 @@ ex power::eval(int level) const
                        if (is_ex_exactly_of_type(sub_exponent,numeric)) {
                                const numeric & num_sub_exponent = ex_to<numeric>(sub_exponent);
                                GINAC_ASSERT(num_sub_exponent!=numeric(1));
-                               if (num_exponent->is_integer() || (abs(num_sub_exponent) - _num1()).is_negative())
+                               if (num_exponent->is_integer() || (abs(num_sub_exponent) - _num1).is_negative())
                                        return power(sub_basis,num_sub_exponent.mul(*num_exponent));
                        }
                }
@@ -422,26 +425,26 @@ ex power::eval(int level) const
                        return expand_mul(ex_to<mul>(ebasis), *num_exponent);
                }
        
-               // ^(*(...,x;c1),c2) -> ^(*(...,x;1),c2)*c1^c2 (c1, c2 numeric(), c1>0)
-               // ^(*(...,x,c1),c2) -> ^(*(...,x;-1),c2)*(-c1)^c2 (c1, c2 numeric(), c1<0)
+               // ^(*(...,x;c1),c2) -> *(^(*(...,x;1),c2),c1^c2)  (c1, c2 numeric(), c1>0)
+               // ^(*(...,x;c1),c2) -> *(^(*(...,x;-1),c2),(-c1)^c2)  (c1, c2 numeric(), c1<0)
                if (is_ex_exactly_of_type(ebasis,mul)) {
                        GINAC_ASSERT(!num_exponent->is_integer()); // should have been handled above
                        const mul & mulref = ex_to<mul>(ebasis);
-                       if (!mulref.overall_coeff.is_equal(_ex1())) {
+                       if (!mulref.overall_coeff.is_equal(_ex1)) {
                                const numeric & num_coeff = ex_to<numeric>(mulref.overall_coeff);
                                if (num_coeff.is_real()) {
                                        if (num_coeff.is_positive()) {
-                                               mul * mulp = new mul(mulref);
-                                               mulp->overall_coeff = _ex1();
+                                               mul *mulp = new mul(mulref);
+                                               mulp->overall_coeff = _ex1;
                                                mulp->clearflag(status_flags::evaluated);
                                                mulp->clearflag(status_flags::hash_calculated);
                                                return (new mul(power(*mulp,exponent),
                                                                power(num_coeff,*num_exponent)))->setflag(status_flags::dynallocated);
                                        } else {
-                                               GINAC_ASSERT(num_coeff.compare(_num0())<0);
-                                               if (num_coeff.compare(_num_1())!=0) {
-                                                       mul * mulp = new mul(mulref);
-                                                       mulp->overall_coeff = _ex_1();
+                                               GINAC_ASSERT(num_coeff.compare(_num0)<0);
+                                               if (!num_coeff.is_equal(_num_1)) {
+                                                       mul *mulp = new mul(mulref);
+                                                       mulp->overall_coeff = _ex_1;
                                                        mulp->clearflag(status_flags::evaluated);
                                                        mulp->clearflag(status_flags::hash_calculated);
                                                        return (new mul(power(*mulp,exponent),
@@ -461,17 +464,15 @@ ex power::eval(int level) const
        }
        
        if (are_ex_trivially_equal(ebasis,basis) &&
-               are_ex_trivially_equal(eexponent,exponent)) {
+           are_ex_trivially_equal(eexponent,exponent)) {
                return this->hold();
        }
        return (new power(ebasis, eexponent))->setflag(status_flags::dynallocated |
-                                                                                                  status_flags::evaluated);
+                                                      status_flags::evaluated);
 }
 
 ex power::evalf(int level) const
 {
-       debugmsg("power evalf",LOGLEVEL_MEMBER_FUNCTION);
-
        ex ebasis;
        ex eexponent;
        
@@ -482,7 +483,7 @@ ex power::evalf(int level) const
                throw(std::runtime_error("max recursion level reached"));
        } else {
                ebasis = basis.evalf(level-1);
-               if (!is_ex_exactly_of_type(eexponent,numeric))
+               if (!is_exactly_a<numeric>(exponent))
                        eexponent = exponent.evalf(level-1);
                else
                        eexponent = exponent;
@@ -493,8 +494,8 @@ ex power::evalf(int level) const
 
 ex power::evalm(void) const
 {
-       ex ebasis = basis.evalm();
-       ex eexponent = exponent.evalm();
+       const ex ebasis = basis.evalm();
+       const ex eexponent = exponent.evalm();
        if (is_ex_of_type(ebasis,matrix)) {
                if (is_ex_of_type(eexponent,numeric)) {
                        return (new matrix(ex_to<matrix>(ebasis).pow(eexponent)))->setflag(status_flags::dynallocated);
@@ -512,7 +513,7 @@ ex power::subs(const lst & ls, const lst & lr, bool no_pattern) const
         && are_ex_trivially_equal(exponent, subsed_exponent))
                return basic::subs(ls, lr, no_pattern);
        else
-               return ex(power(subsed_basis, subsed_exponent)).bp->basic::subs(ls, lr, no_pattern);
+               return power(subsed_basis, subsed_exponent).basic::subs(ls, lr, no_pattern);
 }
 
 ex power::simplify_ncmul(const exvector & v) const
@@ -530,20 +531,20 @@ ex power::derivative(const symbol & s) const
                // D(b^r) = r * b^(r-1) * D(b) (faster than the formula below)
                epvector newseq;
                newseq.reserve(2);
-               newseq.push_back(expair(basis, exponent - _ex1()));
-               newseq.push_back(expair(basis.diff(s), _ex1()));
+               newseq.push_back(expair(basis, exponent - _ex1));
+               newseq.push_back(expair(basis.diff(s), _ex1));
                return mul(newseq, exponent);
        } else {
                // D(b^e) = b^e * (D(e)*ln(b) + e*D(b)/b)
                return mul(*this,
                           add(mul(exponent.diff(s), log(basis)),
-                          mul(mul(exponent, basis.diff(s)), power(basis, _ex_1()))));
+                          mul(mul(exponent, basis.diff(s)), power(basis, _ex_1))));
        }
 }
 
 int power::compare_same_type(const basic & other) const
 {
-       GINAC_ASSERT(is_exactly_of_type(other, power));
+       GINAC_ASSERT(is_exactly_a<power>(other));
        const power &o = static_cast<const power &>(other);
 
        int cmpval = basis.compare(o.basis);
@@ -568,8 +569,8 @@ ex power::expand(unsigned options) const
        if (options == 0 && (flags & status_flags::expanded))
                return *this;
        
-       ex expanded_basis = basis.expand(options);
-       ex expanded_exponent = exponent.expand(options);
+       const ex expanded_basis = basis.expand(options);
+       const ex expanded_exponent = exponent.expand(options);
        
        // x^(a+b) -> x^a * x^b
        if (is_ex_exactly_of_type(expanded_exponent, add)) {
@@ -580,7 +581,7 @@ ex power::expand(unsigned options) const
                epvector::const_iterator cit = a.seq.begin();
                while (cit!=last) {
                        distrseq.push_back(power(expanded_basis, a.recombine_pair_to_ex(*cit)));
-                       cit++;
+                       ++cit;
                }
                
                // Make sure that e.g. (x+y)^(2+a) expands the (x+y)^2 factor
@@ -658,18 +659,18 @@ ex power::expand_add(const add & a, int n) const
                upper_limit[l] = n;
        }
        
-       while (1) {
+       while (true) {
                exvector term;
                term.reserve(m+1);
                for (l=0; l<m-1; l++) {
                        const ex & b = a.op(l);
-                       GINAC_ASSERT(!is_ex_exactly_of_type(b,add));
-                       GINAC_ASSERT(!is_ex_exactly_of_type(b,power) ||
-                                    !is_ex_exactly_of_type(ex_to<power>(b).exponent,numeric) ||
+                       GINAC_ASSERT(!is_exactly_a<add>(b));
+                       GINAC_ASSERT(!is_exactly_a<power>(b) ||
+                                    !is_exactly_a<numeric>(ex_to<power>(b).exponent) ||
                                     !ex_to<numeric>(ex_to<power>(b).exponent).is_pos_integer() ||
-                                    !is_ex_exactly_of_type(ex_to<power>(b).basis,add) ||
-                                    !is_ex_exactly_of_type(ex_to<power>(b).basis,mul) ||
-                                    !is_ex_exactly_of_type(ex_to<power>(b).basis,power));
+                                    !is_exactly_a<add>(ex_to<power>(b).basis) ||
+                                    !is_exactly_a<mul>(ex_to<power>(b).basis) ||
+                                    !is_exactly_a<power>(ex_to<power>(b).basis));
                        if (is_ex_exactly_of_type(b,mul))
                                term.push_back(expand_mul(ex_to<mul>(b),numeric(k[l])));
                        else
@@ -677,13 +678,13 @@ ex power::expand_add(const add & a, int n) const
                }
                
                const ex & b = a.op(l);
-               GINAC_ASSERT(!is_ex_exactly_of_type(b,add));
-               GINAC_ASSERT(!is_ex_exactly_of_type(b,power) ||
-                            !is_ex_exactly_of_type(ex_to<power>(b).exponent,numeric) ||
+               GINAC_ASSERT(!is_exactly_a<add>(b));
+               GINAC_ASSERT(!is_exactly_a<power>(b) ||
+                            !is_exactly_a<numeric>(ex_to<power>(b).exponent) ||
                             !ex_to<numeric>(ex_to<power>(b).exponent).is_pos_integer() ||
-                            !is_ex_exactly_of_type(ex_to<power>(b).basis,add) ||
-                            !is_ex_exactly_of_type(ex_to<power>(b).basis,mul) ||
-                            !is_ex_exactly_of_type(ex_to<power>(b).basis,power));
+                            !is_exactly_a<add>(ex_to<power>(b).basis) ||
+                            !is_exactly_a<mul>(ex_to<power>(b).basis) ||
+                            !is_exactly_a<power>(ex_to<power>(b).basis));
                if (is_ex_exactly_of_type(b,mul))
                        term.push_back(expand_mul(ex_to<mul>(b),numeric(n-k_cum[m-2])));
                else
@@ -695,25 +696,14 @@ ex power::expand_add(const add & a, int n) const
                
                term.push_back(f);
                
-               /*
-               cout << "begin term" << endl;
-               for (int i=0; i<m-1; i++) {
-                       cout << "k[" << i << "]=" << k[i] << endl;
-                       cout << "k_cum[" << i << "]=" << k_cum[i] << endl;
-                       cout << "upper_limit[" << i << "]=" << upper_limit[i] << endl;
-               }
-               for_each(term.begin(), term.end(), ostream_iterator<ex>(cout, "\n"));
-               cout << "end term" << endl;
-               */
-               
-               // TODO: optimize this
+               // TODO: Can we optimize this?  Alex seemed to think so...
                sum.push_back((new mul(term))->setflag(status_flags::dynallocated));
                
                // increment k[]
                l = m-2;
-               while ((l>=0)&&((++k[l])>upper_limit[l])) {
+               while ((l>=0) && ((++k[l])>upper_limit[l])) {
                        k[l] = 0;    
-                       l--;
+                       --l;
                }
                if (l<0) break;
                
@@ -730,7 +720,7 @@ ex power::expand_add(const add & a, int n) const
                        upper_limit[i] = n-k_cum[i-1];
        }
        return (new add(sum))->setflag(status_flags::dynallocated |
-                                                                  status_flags::expanded );
+                                      status_flags::expanded );
 }
 
 
@@ -746,40 +736,40 @@ ex power::expand_add_2(const add & a) const
        // power(+(x,...,z;c),2)=power(+(x,...,z;0),2)+2*c*+(x,...,z;0)+c*c
        // first part: ignore overall_coeff and expand other terms
        for (epvector::const_iterator cit0=a.seq.begin(); cit0!=last; ++cit0) {
-               const ex & r = (*cit0).rest;
-               const ex & c = (*cit0).coeff;
+               const ex & r = cit0->rest;
+               const ex & c = cit0->coeff;
                
-               GINAC_ASSERT(!is_ex_exactly_of_type(r,add));
-               GINAC_ASSERT(!is_ex_exactly_of_type(r,power) ||
-                            !is_ex_exactly_of_type(ex_to<power>(r).exponent,numeric) ||
+               GINAC_ASSERT(!is_exactly_a<add>(r));
+               GINAC_ASSERT(!is_exactly_a<power>(r) ||
+                            !is_exactly_a<numeric>(ex_to<power>(r).exponent) ||
                             !ex_to<numeric>(ex_to<power>(r).exponent).is_pos_integer() ||
-                            !is_ex_exactly_of_type(ex_to<power>(r).basis,add) ||
-                            !is_ex_exactly_of_type(ex_to<power>(r).basis,mul) ||
-                            !is_ex_exactly_of_type(ex_to<power>(r).basis,power));
+                            !is_exactly_a<add>(ex_to<power>(r).basis) ||
+                            !is_exactly_a<mul>(ex_to<power>(r).basis) ||
+                            !is_exactly_a<power>(ex_to<power>(r).basis));
                
-               if (are_ex_trivially_equal(c,_ex1())) {
+               if (are_ex_trivially_equal(c,_ex1)) {
                        if (is_ex_exactly_of_type(r,mul)) {
-                               sum.push_back(expair(expand_mul(ex_to<mul>(r),_num2()),
-                                                    _ex1()));
+                               sum.push_back(expair(expand_mul(ex_to<mul>(r),_num2),
+                                                    _ex1));
                        } else {
-                               sum.push_back(expair((new power(r,_ex2()))->setflag(status_flags::dynallocated),
-                                                    _ex1()));
+                               sum.push_back(expair((new power(r,_ex2))->setflag(status_flags::dynallocated),
+                                                    _ex1));
                        }
                } else {
                        if (is_ex_exactly_of_type(r,mul)) {
-                               sum.push_back(expair(expand_mul(ex_to<mul>(r),_num2()),
-                                                    ex_to<numeric>(c).power_dyn(_num2())));
+                               sum.push_back(expair(expand_mul(ex_to<mul>(r),_num2),
+                                                    ex_to<numeric>(c).power_dyn(_num2)));
                        } else {
-                               sum.push_back(expair((new power(r,_ex2()))->setflag(status_flags::dynallocated),
-                                                    ex_to<numeric>(c).power_dyn(_num2())));
+                               sum.push_back(expair((new power(r,_ex2))->setflag(status_flags::dynallocated),
+                                                    ex_to<numeric>(c).power_dyn(_num2)));
                        }
                }
                        
                for (epvector::const_iterator cit1=cit0+1; cit1!=last; ++cit1) {
-                       const ex & r1 = (*cit1).rest;
-                       const ex & c1 = (*cit1).coeff;
+                       const ex & r1 = cit1->rest;
+                       const ex & c1 = cit1->coeff;
                        sum.push_back(a.combine_ex_with_coeff_to_pair((new mul(r,r1))->setflag(status_flags::dynallocated),
-                                                                     _num2().mul(ex_to<numeric>(c)).mul_dyn(ex_to<numeric>(c1))));
+                                                                     _num2.mul(ex_to<numeric>(c)).mul_dyn(ex_to<numeric>(c1))));
                }
        }
        
@@ -789,10 +779,10 @@ ex power::expand_add_2(const add & a) const
        if (!a.overall_coeff.is_zero()) {
                epvector::const_iterator i = a.seq.begin(), end = a.seq.end();
                while (i != end) {
-                       sum.push_back(a.combine_pair_with_coeff_to_pair(*i, ex_to<numeric>(a.overall_coeff).mul_dyn(_num2())));
+                       sum.push_back(a.combine_pair_with_coeff_to_pair(*i, ex_to<numeric>(a.overall_coeff).mul_dyn(_num2)));
                        ++i;
                }
-               sum.push_back(expair(ex_to<numeric>(a.overall_coeff).power_dyn(_num2()),_ex1()));
+               sum.push_back(expair(ex_to<numeric>(a.overall_coeff).power_dyn(_num2),_ex1));
        }
        
        GINAC_ASSERT(sum.size()==(a_nops*(a_nops+1))/2);
@@ -805,7 +795,7 @@ ex power::expand_add_2(const add & a) const
 ex power::expand_mul(const mul & m, const numeric & n) const
 {
        if (n.is_zero())
-               return _ex1();
+               return _ex1;
        
        epvector distrseq;
        distrseq.reserve(m.seq.size());
@@ -824,23 +814,4 @@ ex power::expand_mul(const mul & m, const numeric & n) const
        return (new mul(distrseq,ex_to<numeric>(m.overall_coeff).power_dyn(n)))->setflag(status_flags::dynallocated);
 }
 
-/*
-ex power::expand_noncommutative(const ex & basis, const numeric & exponent,
-                                                               unsigned options) const
-{
-       ex rest_power = ex(power(basis,exponent.add(_num_1()))).
-                       expand(options | expand_options::internal_do_not_expand_power_operands);
-
-       return ex(mul(rest_power,basis),0).
-              expand(options | expand_options::internal_do_not_expand_mul_operands);
-}
-*/
-
-// helper function
-
-ex sqrt(const ex & a)
-{
-       return power(a,_ex1_2());
-}
-
 } // namespace GiNaC