]> www.ginac.de Git - ginac.git/blobdiff - ginac/power.cpp
Convert some more ctors from copying to moving STL containers.
[ginac.git] / ginac / power.cpp
index 2106b5113c6e26a5c60ebdb57c10991d661a4572..bf48e93eb3fdc334703dac1aa72aec72ff492b32 100644 (file)
@@ -524,8 +524,8 @@ ex power::eval(int level) const
                                addp->setflag(status_flags::dynallocated);
                                addp->clearflag(status_flags::hash_calculated);
                                addp->overall_coeff = ex_to<numeric>(addp->overall_coeff).div_dyn(icont);
-                               for (epvector::iterator i = addp->seq.begin(); i != addp->seq.end(); ++i)
-                                       i->coeff = ex_to<numeric>(i->coeff).div_dyn(icont);
+                               for (auto & i : addp->seq)
+                                       i.coeff = ex_to<numeric>(i.coeff).div_dyn(icont);
 
                                const numeric c = icont.power(*num_exponent);
                                if (likely(c != *_num1_p))
@@ -571,7 +571,7 @@ ex power::eval(int level) const
                if (num_exponent->is_pos_integer() &&
                    ebasis.return_type() != return_types::commutative &&
                    !is_a<matrix>(ebasis)) {
-                       return ncmul(exvector(num_exponent->to_int(), ebasis), true);
+                       return ncmul(exvector(num_exponent->to_int(), ebasis));
                }
        }
        
@@ -653,12 +653,12 @@ ex power::subs(const exmap & m, unsigned options) const
        if (!(options & subs_options::algebraic))
                return subs_one_level(m, options);
 
-       for (exmap::const_iterator it = m.begin(); it != m.end(); ++it) {
+       for (auto & it : m) {
                int nummatches = std::numeric_limits<int>::max();
                exmap repls;
-               if (tryfactsubs(*this, it->first, nummatches, repls)) {
-                       ex anum = it->second.subs(repls, subs_options::no_pattern);
-                       ex aden = it->first.subs(repls, subs_options::no_pattern);
+               if (tryfactsubs(*this, it.first, nummatches, repls)) {
+                       ex anum = it.second.subs(repls, subs_options::no_pattern);
+                       ex aden = it.first.subs(repls, subs_options::no_pattern);
                        ex result = (*this)*power(anum/aden, nummatches);
                        return (ex_to<basic>(result)).subs_one_level(m, options);
                }
@@ -695,51 +695,71 @@ ex power::conjugate() const
 
 ex power::real_part() const
 {
+       // basis == a+I*b, exponent == c+I*d
+       const ex a = basis.real_part();
+       const ex c = exponent.real_part();
+       if (basis.is_equal(a) && exponent.is_equal(c)) {
+               // Re(a^c)
+               return *this;
+       }
+
+       const ex b = basis.imag_part();
        if (exponent.info(info_flags::integer)) {
-               ex basis_real = basis.real_part();
-               if (basis_real == basis)
-                       return *this;
-               realsymbol a("a"),b("b");
-               ex result;
-               if (exponent.info(info_flags::posint))
-                       result = power(a+I*b,exponent);
-               else
-                       result = power(a/(a*a+b*b)-I*b/(a*a+b*b),-exponent);
-               result = result.expand();
-               result = result.real_part();
-               result = result.subs(lst( a==basis_real, b==basis.imag_part() ));
+               // Re((a+I*b)^c)  w/  c ∈ ℤ
+               long N = ex_to<numeric>(c).to_long();
+               // Use real terms in Binomial expansion to construct
+               // Re(expand(power(a+I*b, N))).
+               long NN = N > 0 ? N : -N;
+               ex numer = N > 0 ? _ex1 : power(power(a,2) + power(b,2), NN);
+               ex result = 0;
+               for (long n = 0; n <= NN; n += 2) {
+                       ex term = binomial(NN, n) * power(a, NN-n) * power(b, n) / numer;
+                       if (n % 4 == 0) {
+                               result += term;  // sign: I^n w/ n == 4*m
+                       } else {
+                               result -= term;  // sign: I^n w/ n == 4*m+2
+                       }
+               }
                return result;
        }
-       
-       ex a = basis.real_part();
-       ex b = basis.imag_part();
-       ex c = exponent.real_part();
-       ex d = exponent.imag_part();
+
+       // Re((a+I*b)^(c+I*d))
+       const ex d = exponent.imag_part();
        return power(abs(basis),c)*exp(-d*atan2(b,a))*cos(c*atan2(b,a)+d*log(abs(basis)));
 }
 
 ex power::imag_part() const
 {
+       const ex a = basis.real_part();
+       const ex c = exponent.real_part();
+       if (basis.is_equal(a) && exponent.is_equal(c)) {
+               // Im(a^c)
+               return 0;
+       }
+
+       const ex b = basis.imag_part();
        if (exponent.info(info_flags::integer)) {
-               ex basis_real = basis.real_part();
-               if (basis_real == basis)
-                       return 0;
-               realsymbol a("a"),b("b");
-               ex result;
-               if (exponent.info(info_flags::posint))
-                       result = power(a+I*b,exponent);
-               else
-                       result = power(a/(a*a+b*b)-I*b/(a*a+b*b),-exponent);
-               result = result.expand();
-               result = result.imag_part();
-               result = result.subs(lst( a==basis_real, b==basis.imag_part() ));
+               // Im((a+I*b)^c)  w/  c ∈ ℤ
+               long N = ex_to<numeric>(c).to_long();
+               // Use imaginary terms in Binomial expansion to construct
+               // Im(expand(power(a+I*b, N))).
+               long p = N > 0 ? 1 : 3;  // modulus for positive sign
+               long NN = N > 0 ? N : -N;
+               ex numer = N > 0 ? _ex1 : power(power(a,2) + power(b,2), NN);
+               ex result = 0;
+               for (long n = 1; n <= NN; n += 2) {
+                       ex term = binomial(NN, n) * power(a, NN-n) * power(b, n) / numer;
+                       if (n % 4 == p) {
+                               result += term;  // sign: I^n w/ n == 4*m+p
+                       } else {
+                               result -= term;  // sign: I^n w/ n == 4*m+2+p
+                       }
+               }
                return result;
        }
-       
-       ex a=basis.real_part();
-       ex b=basis.imag_part();
-       ex c=exponent.real_part();
-       ex d=exponent.imag_part();
+
+       // Im((a+I*b)^(c+I*d))
+       const ex d = exponent.imag_part();
        return power(abs(basis),c)*exp(-d*atan2(b,a))*sin(c*atan2(b,a)+d*log(abs(basis)));
 }
 
@@ -755,7 +775,7 @@ ex power::derivative(const symbol & s) const
                newseq.reserve(2);
                newseq.push_back(expair(basis, exponent - _ex1));
                newseq.push_back(expair(basis.diff(s), _ex1));
-               return mul(newseq, exponent);
+               return mul(std::move(newseq), exponent);
        } else {
                // D(b^e) = b^e * (D(e)*ln(b) + e*D(b)/b)
                return mul(*this,
@@ -802,21 +822,18 @@ ex power::expand(unsigned options) const
                epvector powseq;
                prodseq.reserve(m.seq.size() + 1);
                powseq.reserve(m.seq.size() + 1);
-               epvector::const_iterator last = m.seq.end();
-               epvector::const_iterator cit = m.seq.begin();
                bool possign = true;
 
                // search for positive/negative factors
-               while (cit!=last) {
-                       ex e=m.recombine_pair_to_ex(*cit);
+               for (auto & cit : m.seq) {
+                       ex e=m.recombine_pair_to_ex(cit);
                        if (e.info(info_flags::positive))
                                prodseq.push_back(pow(e, exponent).expand(options));
                        else if (e.info(info_flags::negative)) {
                                prodseq.push_back(pow(-e, exponent).expand(options));
                                possign = !possign;
                        } else
-                               powseq.push_back(*cit);
-                       ++cit;
+                               powseq.push_back(cit);
                }
 
                // take care on the numeric coefficient
@@ -832,9 +849,9 @@ ex power::expand(unsigned options) const
                // In either case we set a flag to avoid the second run on a part
                // which does not have positive/negative terms.
                if (prodseq.size() > 0) {
-                       ex newbasis = coeff*mul(powseq);
+                       ex newbasis = coeff*mul(std::move(powseq));
                        ex_to<basic>(newbasis).setflag(status_flags::purely_indefinite);
-                       return ((new mul(prodseq))->setflag(status_flags::dynallocated)*(new power(newbasis, exponent))->setflag(status_flags::dynallocated).expand(options)).expand(options);
+                       return ((new mul(std::move(prodseq)))->setflag(status_flags::dynallocated)*(new power(newbasis, exponent))->setflag(status_flags::dynallocated).expand(options)).expand(options);
                } else
                        ex_to<basic>(basis).setflag(status_flags::purely_indefinite);
        }
@@ -847,11 +864,8 @@ ex power::expand(unsigned options) const
                const add &a = ex_to<add>(expanded_exponent);
                exvector distrseq;
                distrseq.reserve(a.seq.size() + 1);
-               epvector::const_iterator last = a.seq.end();
-               epvector::const_iterator cit = a.seq.begin();
-               while (cit!=last) {
-                       distrseq.push_back(power(expanded_basis, a.recombine_pair_to_ex(*cit)));
-                       ++cit;
+               for (auto & cit : a.seq) {
+                       distrseq.push_back(power(expanded_basis, a.recombine_pair_to_ex(cit)));
                }
                
                // Make sure that e.g. (x+y)^(2+a) expands the (x+y)^2 factor
@@ -1006,8 +1020,8 @@ private:
                element *head, *i, *after_i;
                // NB: Partition must be sorted in non-decreasing order.
                explicit coolmulti(const std::vector<int>& partition)
+                 : head(nullptr), i(nullptr), after_i(nullptr)
                {
-                       head = nullptr;
                        for (unsigned n = 0; n < partition.size(); ++n) {
                                head = new element(partition[n], head);
                                if (n <= 1)
@@ -1077,14 +1091,12 @@ public:
  *  where n = p1+p2+...+pk, i.e. p is a partition of n.
  */
 const numeric
-multinomial_coefficient(const std::vector<int> p)
+multinomial_coefficient(const std::vector<int> p)
 {
        numeric n = 0, d = 1;
-       std::vector<int>::const_iterator it = p.begin(), itend = p.end();
-       while (it != itend) {
-               n += numeric(*it);
-               d *= factorial(numeric(*it));
-               ++it;
+       for (auto & it : p) {
+               n += numeric(it);
+               d *= factorial(numeric(it));
        }
        return factorial(numeric(n)) / d;
 }
@@ -1195,7 +1207,6 @@ ex power::expand_add(const add & a, int n, unsigned options) const
                                numeric factor = coeff;
                                for (unsigned i = 0; i < exponent.size(); ++i) {
                                        const ex & r = a.seq[i].rest;
-                                       const ex & c = a.seq[i].coeff;
                                        GINAC_ASSERT(!is_exactly_a<add>(r));
                                        GINAC_ASSERT(!is_exactly_a<power>(r) ||
                                                     !is_exactly_a<numeric>(ex_to<power>(r).exponent) ||
@@ -1203,15 +1214,19 @@ ex power::expand_add(const add & a, int n, unsigned options) const
                                                     !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));
+                                       GINAC_ASSERT(is_exactly_a<numeric>(a.seq[i].coeff));
+                                       const numeric & c = ex_to<numeric>(a.seq[i].coeff);
                                        if (exponent[i] == 0) {
                                                // optimize away
                                        } else if (exponent[i] == 1) {
                                                // optimized
                                                term.push_back(r);
-                                               factor = factor.mul(ex_to<numeric>(c));
+                                               if (c != *_num1_p)
+                                                       factor = factor.mul(c);
                                        } else { // general case exponent[i] > 1
                                                term.push_back((new power(r, exponent[i]))->setflag(status_flags::dynallocated));
-                                               factor = factor.mul(ex_to<numeric>(c).power(exponent[i]));
+                                               if (c != *_num1_p)
+                                                       factor = factor.mul(c.power(exponent[i]));
                                        }
                                }
                                result.push_back(a.combine_ex_with_coeff_to_pair(mul(term).expand(options), factor));
@@ -1222,11 +1237,11 @@ ex power::expand_add(const add & a, int n, unsigned options) const
        GINAC_ASSERT(result.size() == result_size);
 
        if (a.overall_coeff.is_zero()) {
-               return (new add(result))->setflag(status_flags::dynallocated |
-                                                 status_flags::expanded);
+               return (new add(std::move(result)))->setflag(status_flags::dynallocated |
+                                                            status_flags::expanded);
        } else {
-               return (new add(result, ex_to<numeric>(a.overall_coeff).power(n)))->setflag(status_flags::dynallocated |
-                                                                                           status_flags::expanded);
+               return (new add(std::move(result), ex_to<numeric>(a.overall_coeff).power(n)))->setflag(status_flags::dynallocated |
+                                                                                                      status_flags::expanded);
        }
 }
 
@@ -1294,7 +1309,7 @@ ex power::expand_add_2(const add & a, unsigned options) const
        
        GINAC_ASSERT(sum.size()==(a_nops*(a_nops+1))/2);
        
-       return (new add(sum))->setflag(status_flags::dynallocated | status_flags::expanded);
+       return (new add(std::move(sum)))->setflag(status_flags::dynallocated | status_flags::expanded);
 }
 
 /** Expand factors of m in m^n where m is a mul and n is an integer.
@@ -1327,17 +1342,14 @@ ex power::expand_mul(const mul & m, const numeric & n, unsigned options, bool fr
        distrseq.reserve(m.seq.size());
        bool need_reexpand = false;
 
-       epvector::const_iterator last = m.seq.end();
-       epvector::const_iterator cit = m.seq.begin();
-       while (cit!=last) {
-               expair p = m.combine_pair_with_coeff_to_pair(*cit, n);
-               if (from_expand && is_exactly_a<add>(cit->rest) && ex_to<numeric>(p.coeff).is_pos_integer()) {
+       for (auto & cit : m.seq) {
+               expair p = m.combine_pair_with_coeff_to_pair(cit, n);
+               if (from_expand && is_exactly_a<add>(cit.rest) && ex_to<numeric>(p.coeff).is_pos_integer()) {
                        // this happens when e.g. (a+b)^(1/2) gets squared and
                        // the resulting product needs to be reexpanded
                        need_reexpand = true;
                }
                distrseq.push_back(p);
-               ++cit;
        }
 
        const mul & result = static_cast<const mul &>((new mul(distrseq, ex_to<numeric>(m.overall_coeff).power_dyn(n)))->setflag(status_flags::dynallocated));