]> www.ginac.de Git - ginac.git/blobdiff - ginac/factor.cpp
Minor sreamlining of some internal code using class lst...
[ginac.git] / ginac / factor.cpp
index da870d3daf079a2d202376177074dbbc897e84e2..2c0ab8a5c07b04ab37aea5a78e4e22996fab9821 100644 (file)
@@ -33,7 +33,7 @@
  */
 
 /*
- *  GiNaC Copyright (C) 1999-2008 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2017 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
@@ -70,6 +70,7 @@
 #include <limits>
 #include <list>
 #include <vector>
+#include <stack>
 #ifdef DEBUGFACTOR
 #include <ostream>
 #endif
@@ -86,15 +87,16 @@ namespace GiNaC {
 #define DCOUT2(str,var) cout << #str << ": " << var << endl
 ostream& operator<<(ostream& o, const vector<int>& v)
 {
-       vector<int>::const_iterator i = v.begin(), end = v.end();
+       auto i = v.begin(), end = v.end();
        while ( i != end ) {
-               o << *i++ << " ";
+               o << *i << " ";
+               ++i;
        }
        return o;
 }
 static ostream& operator<<(ostream& o, const vector<cl_I>& v)
 {
-       vector<cl_I>::const_iterator i = v.begin(), end = v.end();
+       auto i = v.begin(), end = v.end();
        while ( i != end ) {
                o << *i << "[" << i-v.begin() << "]" << " ";
                ++i;
@@ -103,7 +105,7 @@ static ostream& operator<<(ostream& o, const vector<cl_I>& v)
 }
 static ostream& operator<<(ostream& o, const vector<cl_MI>& v)
 {
-       vector<cl_MI>::const_iterator i = v.begin(), end = v.end();
+       auto i = v.begin(), end = v.end();
        while ( i != end ) {
                o << *i << "[" << i-v.begin() << "]" << " ";
                ++i;
@@ -117,9 +119,9 @@ ostream& operator<<(ostream& o, const vector<numeric>& v)
        }
        return o;
 }
-ostream& operator<<(ostream& o, const vector< vector<cl_MI> >& v)
+ostream& operator<<(ostream& o, const vector<vector<cl_MI>>& v)
 {
-       vector< vector<cl_MI> >::const_iterator i = v.begin(), end = v.end();
+       auto i = v.begin(), end = v.end();
        while ( i != end ) {
                o << i-v.begin() << ": " << *i << endl;
                ++i;
@@ -218,8 +220,32 @@ static void expt_pos(umodpoly& a, unsigned int q)
        }
 }
 
+template<bool COND, typename T = void> struct enable_if
+{
+       typedef T type;
+};
+
+template<typename T> struct enable_if<false, T> { /* empty */ };
+
+template<typename T> struct uvar_poly_p
+{
+       static const bool value = false;
+};
+
+template<> struct uvar_poly_p<upoly>
+{
+       static const bool value = true;
+};
+
+template<> struct uvar_poly_p<umodpoly>
+{
+       static const bool value = true;
+};
+
 template<typename T>
-static T operator+(const T& a, const T& b)
+// Don't define this for anything but univariate polynomials.
+static typename enable_if<uvar_poly_p<T>::value, T>::type
+operator+(const T& a, const T& b)
 {
        int sa = a.size();
        int sb = b.size();
@@ -250,7 +276,11 @@ static T operator+(const T& a, const T& b)
 }
 
 template<typename T>
-static T operator-(const T& a, const T& b)
+// Don't define this for anything but univariate polynomials. Otherwise
+// overload resolution might fail (this actually happens when compiling
+// GiNaC with g++ 3.4).
+static typename enable_if<uvar_poly_p<T>::value, T>::type
+operator-(const T& a, const T& b)
 {
        int sa = a.size();
        int sb = b.size();
@@ -470,11 +500,10 @@ static void reduce_coeff(umodpoly& a, const cl_I& x)
        if ( a.empty() ) return;
 
        cl_modint_ring R = a[0].ring();
-       umodpoly::iterator i = a.begin(), end = a.end();
-       for ( ; i!=end; ++i ) {
+       for (auto & i : a) {
                // cln cannot perform this division in the modular field
-               cl_I c = R->retract(*i);
-               *i = cl_MI(R, the<cl_I>(c / x));
+               cl_I c = R->retract(i);
+               i = cl_MI(R, the<cl_I>(c / x));
        }
 }
 
@@ -651,7 +680,9 @@ typedef vector<cl_MI> mvec;
 
 class modular_matrix
 {
+#ifdef DEBUGFACTOR
        friend ostream& operator<<(ostream& o, const modular_matrix& m);
+#endif
 public:
        modular_matrix(size_t r_, size_t c_, const cl_MI& init) : r(r_), c(c_)
        {
@@ -663,90 +694,75 @@ public:
        cl_MI operator()(size_t row, size_t col) const { return m[row*c + col]; }
        void mul_col(size_t col, const cl_MI x)
        {
-               mvec::iterator i = m.begin() + col;
                for ( size_t rc=0; rc<r; ++rc ) {
-                       *i = *i * x;
-                       i += c;
+                       std::size_t i = c*rc + col;
+                       m[i] = m[i] * x;
                }
        }
        void sub_col(size_t col1, size_t col2, const cl_MI fac)
        {
-               mvec::iterator i1 = m.begin() + col1;
-               mvec::iterator i2 = m.begin() + col2;
                for ( size_t rc=0; rc<r; ++rc ) {
-                       *i1 = *i1 - *i2 * fac;
-                       i1 += c;
-                       i2 += c;
+                       std::size_t i1 = col1 + c*rc;
+                       std::size_t i2 = col2 + c*rc;
+                       m[i1] = m[i1] - m[i2]*fac;
                }
        }
        void switch_col(size_t col1, size_t col2)
        {
-               cl_MI buf;
-               mvec::iterator i1 = m.begin() + col1;
-               mvec::iterator i2 = m.begin() + col2;
                for ( size_t rc=0; rc<r; ++rc ) {
-                       buf = *i1; *i1 = *i2; *i2 = buf;
-                       i1 += c;
-                       i2 += c;
+                       std::size_t i1 = col1 + rc*c;
+                       std::size_t i2 = col2 + rc*c;
+                       std::swap(m[i1], m[i2]);
                }
        }
        void mul_row(size_t row, const cl_MI x)
        {
-               vector<cl_MI>::iterator i = m.begin() + row*c;
                for ( size_t cc=0; cc<c; ++cc ) {
-                       *i = *i * x;
-                       ++i;
+                       std::size_t i = row*c + cc; 
+                       m[i] = m[i] * x;
                }
        }
        void sub_row(size_t row1, size_t row2, const cl_MI fac)
        {
-               vector<cl_MI>::iterator i1 = m.begin() + row1*c;
-               vector<cl_MI>::iterator i2 = m.begin() + row2*c;
                for ( size_t cc=0; cc<c; ++cc ) {
-                       *i1 = *i1 - *i2 * fac;
-                       ++i1;
-                       ++i2;
+                       std::size_t i1 = row1*c + cc;
+                       std::size_t i2 = row2*c + cc;
+                       m[i1] = m[i1] - m[i2]*fac;
                }
        }
        void switch_row(size_t row1, size_t row2)
        {
-               cl_MI buf;
-               vector<cl_MI>::iterator i1 = m.begin() + row1*c;
-               vector<cl_MI>::iterator i2 = m.begin() + row2*c;
                for ( size_t cc=0; cc<c; ++cc ) {
-                       buf = *i1; *i1 = *i2; *i2 = buf;
-                       ++i1;
-                       ++i2;
+                       std::size_t i1 = row1*c + cc;
+                       std::size_t i2 = row2*c + cc;
+                       std::swap(m[i1], m[i2]);
                }
        }
        bool is_col_zero(size_t col) const
        {
-               mvec::const_iterator i = m.begin() + col;
                for ( size_t rr=0; rr<r; ++rr ) {
-                       if ( !zerop(*i) ) {
+                       std::size_t i = col + rr*c;
+                       if ( !zerop(m[i]) ) {
                                return false;
                        }
-                       i += c;
                }
                return true;
        }
        bool is_row_zero(size_t row) const
        {
-               mvec::const_iterator i = m.begin() + row*c;
                for ( size_t cc=0; cc<c; ++cc ) {
-                       if ( !zerop(*i) ) {
+                       std::size_t i = row*c + cc;
+                       if ( !zerop(m[i]) ) {
                                return false;
                        }
-                       ++i;
                }
                return true;
        }
        void set_row(size_t row, const vector<cl_MI>& newrow)
        {
-               mvec::iterator i1 = m.begin() + row*c;
-               mvec::const_iterator i2 = newrow.begin(), end = newrow.end();
-               for ( ; i2 != end; ++i1, ++i2 ) {
-                       *i1 = *i2;
+               for (std::size_t i2 = 0; i2 < newrow.size(); ++i2) {
+                       std::size_t i1 = row*c + i2;
+                       m[i1] = newrow[i2];
                }
        }
        mvec::const_iterator row_begin(size_t row) const { return m.begin()+row*c; }
@@ -900,8 +916,7 @@ static void berlekamp(const umodpoly& a, upvec& upv)
                return;
        }
 
-       list<umodpoly> factors;
-       factors.push_back(a);
+       list<umodpoly> factors = {a};
        unsigned int size = 1;
        unsigned int r = 1;
        unsigned int q = cl_I_to_uint(R->modulus);
@@ -921,21 +936,18 @@ static void berlekamp(const umodpoly& a, upvec& upv)
                                div(*u, g, uo);
                                if ( equal_one(uo) ) {
                                        throw logic_error("berlekamp: unexpected divisor.");
-                               }
-                               else {
+                               } else {
                                        *u = uo;
                                }
                                factors.push_back(g);
                                size = 0;
-                               list<umodpoly>::const_iterator i = factors.begin(), end = factors.end();
-                               while ( i != end ) {
-                                       if ( degree(*i) ) ++size; 
-                                       ++i;
+                               for (auto & i : factors) {
+                                       if (degree(i))
+                                               ++size;
                                }
                                if ( size == k ) {
-                                       list<umodpoly>::const_iterator i = factors.begin(), end = factors.end();
-                                       while ( i != end ) {
-                                               upv.push_back(*i++);
+                                       for (auto & i : factors) {
+                                               upv.push_back(i);
                                        }
                                        return;
                                }
@@ -1007,8 +1019,7 @@ static void modsqrfree(const umodpoly& a, upvec& factors, vector<int>& mult)
                                mult[i] *= prime;
                        }
                }
-       }
-       else {
+       } else {
                umodpoly ap;
                expt_1_over_p(a, prime, ap);
                size_t previ = mult.size();
@@ -1093,8 +1104,7 @@ static void same_degree_factor(const umodpoly& a, upvec& upv)
        for ( size_t i=0; i<degrees.size(); ++i ) {
                if ( degrees[i] == degree(ddfactors[i]) ) {
                        upv.push_back(ddfactors[i]);
-               }
-               else {
+               } else {
                        berlekamp(ddfactors[i], upv);
                }
        }
@@ -1159,15 +1169,13 @@ static void exteuclid(const umodpoly& a, const umodpoly& b, umodpoly& s, umodpol
                d2 = r2;
        }
        cl_MI fac = recip(lcoeff(a) * lcoeff(c));
-       umodpoly::iterator i = s.begin(), end = s.end();
-       for ( ; i!=end; ++i ) {
-               *i = *i * fac;
+       for (auto & i : s) {
+               i = i * fac;
        }
        canonicalize(s);
        fac = recip(lcoeff(b) * lcoeff(c));
-       i = t.begin(), end = t.end();
-       for ( ; i!=end; ++i ) {
-               *i = *i * fac;
+       for (auto & i : t) {
+               i = i * fac;
        }
        canonicalize(t);
 }
@@ -1302,8 +1310,7 @@ static void hensel_univar(const upoly& a_, unsigned int p, const umodpoly& u1_,
                if ( alpha != 1 ) {
                        w = w / alpha;
                }
-       }
-       else {
+       } else {
                u.clear();
        }
 }
@@ -1316,28 +1323,28 @@ static void hensel_univar(const upoly& a_, unsigned int p, const umodpoly& u1_,
 static unsigned int next_prime(unsigned int p)
 {
        static vector<unsigned int> primes;
-       if ( primes.size() == 0 ) {
-               primes.push_back(3); primes.push_back(5); primes.push_back(7);
+       if (primes.empty()) {
+               primes = {3, 5, 7};
        }
-       vector<unsigned int>::const_iterator it = primes.begin();
        if ( p >= primes.back() ) {
                unsigned int candidate = primes.back() + 2;
                while ( true ) {
                        size_t n = primes.size()/2;
                        for ( size_t i=0; i<n; ++i ) {
-                               if ( candidate % primes[i] ) continue;
+                               if (candidate % primes[i])
+                                       continue;
                                candidate += 2;
                                i=-1;
                        }
                        primes.push_back(candidate);
-                       if ( candidate > p ) break;
+                       if (candidate > p)
+                               break;
                }
                return candidate;
        }
-       vector<unsigned int>::const_iterator end = primes.end();
-       for ( ; it!=end; ++it ) {
-               if ( *it > p ) {
-                       return *it;
+       for (auto & it : primes) {
+               if ( it > p ) {
+                       return it;
                }
        }
        throw logic_error("next_prime: should not reach this point!");
@@ -1395,8 +1402,7 @@ public:
                        if ( len > n/2 ) return false;
                        fill(k.begin(), k.begin()+len, 1);
                        fill(k.begin()+len+1, k.end(), 0);
-               }
-               else {
+               } else {
                        k[last++] = 0;
                        k[last] = 1;
                }
@@ -1419,8 +1425,7 @@ private:
                        if ( d ) {
                                if ( cache[pos].size() >= d ) {
                                        lr[group] = lr[group] * cache[pos][d-1];
-                               }
-                               else {
+                               } else {
                                        if ( cache[pos].size() == 0 ) {
                                                cache[pos].push_back(factors[pos] * factors[pos+1]);
                                        }
@@ -1434,8 +1439,7 @@ private:
                                        }
                                        lr[group] = lr[group] * cache[pos].back();
                                }
-                       }
-                       else {
+                       } else {
                                lr[group] = lr[group] * factors[pos];
                        }
                } while ( i < n );
@@ -1446,8 +1450,7 @@ private:
                lr[1] = one;
                if ( n > 6 ) {
                        split_cached();
-               }
-               else {
+               } else {
                        for ( size_t i=0; i<n; ++i ) {
                                lr[k[i]] = lr[k[i]] * factors[i];
                        }
@@ -1455,7 +1458,7 @@ private:
        }
 private:
        umodpoly lr[2];
-       vector< vector<umodpoly> > cache;
+       vector<vector<umodpoly>> cache;
        upvec factors;
        umodpoly one;
        size_t n;
@@ -1496,7 +1499,17 @@ static ex factor_univariate(const ex& poly, const ex& x, unsigned int& prime)
        cl_modint_ring R;
        unsigned int trials = 0;
        unsigned int minfactors = 0;
-       cl_I lc = lcoeff(prim) * the<cl_I>(ex_to<numeric>(cont).to_cl_N());
+
+       const numeric& cont_n = ex_to<numeric>(cont);
+       cl_I i_cont;
+       if (cont_n.is_integer()) {
+               i_cont = the<cl_I>(cont_n.to_cl_N());
+       } else {
+               // poly \in Q[x] => poly = q ipoly, ipoly \in Z[x], q \in Q
+               // factor(poly) \equiv q factor(ipoly)
+               i_cont = cl_I(1);
+       }
+       cl_I lc = lcoeff(prim)*i_cont;
        upvec factors;
        while ( trials < 2 ) {
                umodpoly modpoly;
@@ -1522,8 +1535,7 @@ static ex factor_univariate(const ex& poly, const ex& x, unsigned int& prime)
                        minfactors = trialfactors.size();
                        lastp = prime;
                        trials = 1;
-               }
-               else {
+               } else {
                        ++trials;
                }
        }
@@ -1577,15 +1589,13 @@ static ex factor_univariate(const ex& poly, const ex& x, unsigned int& prime)
                                                }
                                        }
                                        break;
-                               }
-                               else {
+                               } else {
                                        upvec newfactors1(part.size_left()), newfactors2(part.size_right());
-                                       upvec::iterator i1 = newfactors1.begin(), i2 = newfactors2.begin();
+                                       auto i1 = newfactors1.begin(), i2 = newfactors2.begin();
                                        for ( size_t i=0; i<n; ++i ) {
                                                if ( part[i] ) {
                                                        *i2++ = tocheck.top().factors[i];
-                                               }
-                                               else {
+                                               } else {
                                                        *i1++ = tocheck.top().factors[i];
                                                }
                                        }
@@ -1597,8 +1607,7 @@ static ex factor_univariate(const ex& poly, const ex& x, unsigned int& prime)
                                        tocheck.push(mf);
                                        break;
                                }
-                       }
-                       else {
+                       } else {
                                // not successful
                                if ( !part.next() ) {
                                        // if no more combinations left, return polynomial as
@@ -1696,9 +1705,8 @@ static void change_modulus(const cl_modint_ring& R, umodpoly& a)
 {
        if ( a.empty() ) return;
        cl_modint_ring oldR = a[0].ring();
-       umodpoly::iterator i = a.begin(), end = a.end();
-       for ( ; i!=end; ++i ) {
-               *i = R->canonhom(oldR->retract(*i));
+       for (auto & i : a) {
+               i = R->canonhom(oldR->retract(i));
        }
        canonicalize(a);
 }
@@ -1789,8 +1797,7 @@ static upvec univar_diophant(const upvec& a, const ex& x, unsigned int m, unsign
                        rem(bmod, a[j], buf);
                        result.push_back(buf);
                }
-       }
-       else {
+       } else {
                umodpoly s, t;
                eea_lift(a[1], a[0], x, p, k, s, t);
                umodpoly bmod = umodpoly_to_umodpoly(s, R, m);
@@ -1812,7 +1819,7 @@ static upvec univar_diophant(const upvec& a, const ex& x, unsigned int m, unsign
 struct make_modular_map : public map_function {
        cl_modint_ring R;
        make_modular_map(const cl_modint_ring& R_) : R(R_) { }
-       ex operator()(const ex& e)
+       ex operator()(const ex& e) override
        {
                if ( is_a<add>(e) || is_a<mul>(e) ) {
                        return e.map(*this);
@@ -1824,8 +1831,7 @@ struct make_modular_map : public map_function {
                        numeric n(R->retract(emod));
                        if ( n > halfmod ) {
                                return n-mod;
-                       }
-                       else {
+                       } else {
                                return n;
                        }
                }
@@ -1918,8 +1924,7 @@ static vector<ex> multivar_diophant(const vector<ex>& a_, const ex& x, const ex&
                                e = make_modular(buf, R);
                        }
                }
-       }
-       else {
+       } else {
                upvec amod;
                for ( size_t i=0; i<a.size(); ++i ) {
                        umodpoly up;
@@ -1933,8 +1938,7 @@ static vector<ex> multivar_diophant(const vector<ex>& a_, const ex& x, const ex&
                if ( is_a<add>(c) ) {
                        nterms = c.nops();
                        z = c.op(0);
-               }
-               else {
+               } else {
                        nterms = 1;
                        z = c;
                }
@@ -2066,15 +2070,9 @@ static ex hensel_multivar(const ex& a, const ex& x, const vector<EvalPoint>& I,
                acand *= U[i];
        }
        if ( expand(a-acand).is_zero() ) {
-               lst res;
-               for ( size_t i=0; i<U.size(); ++i ) {
-                       res.append(U[i]);
-               }
-               return res;
-       }
-       else {
-               lst res;
-               return lst();
+               return lst(U.begin(), U.end());
+       } else {
+               return lst{};
        }
 }
 
@@ -2095,8 +2093,9 @@ static ex put_factors_into_lst(const ex& e)
                return result;
        }
        if ( is_a<symbol>(e) || is_a<add>(e) ) {
-               result.append(1);
-               result.append(e);
+               ex icont(e.integer_content());
+               result.append(icont);
+               result.append(e/icont);
                return result;
        }
        if ( is_a<mul>(e) ) {
@@ -2247,7 +2246,7 @@ static ex factor_multivariate(const ex& poly, const exset& syms)
        ex vn = pp.collect(x).lcoeff(x);
        ex vnlst;
        if ( is_a<numeric>(vn) ) {
-               vnlst = lst(vn);
+               vnlst = lst{vn};
        }
        else {
                ex vnfactors = factor(vn);
@@ -2305,8 +2304,7 @@ static ex factor_multivariate(const ex& poly, const exset& syms)
                        for ( size_t i=1; i<ufaclst.nops(); ++i ) {
                                C[i-1] = ufaclst.op(i).lcoeff(x);
                        }
-               }
-               else {
+               } else {
                        // difficult case.
                        // we use the property of the ftilde having a unique prime factor.
                        // details can be found in [Wan].
@@ -2341,8 +2339,7 @@ static ex factor_multivariate(const ex& poly, const exset& syms)
                                        }
                                        C[i] = D[i] * prefac;
                                }
-                       }
-                       else {
+                       } else {
                                for ( int i=0; i<factor_count; ++i ) {
                                        numeric prefac = ex_to<numeric>(ufaclst.op(i+1).lcoeff(x));
                                        for ( int j=ftilde.size()-1; j>=0; --j ) {
@@ -2421,7 +2418,7 @@ static ex factor_multivariate(const ex& poly, const exset& syms)
 
                // try Hensel lifting
                ex res = hensel_multivar(pp, x, epv, prime, l, modfactors, C);
-               if ( res != lst() ) {
+               if ( res != lst{} ) {
                        ex result = cont * unit;
                        for ( size_t i=0; i<res.nops(); ++i ) {
                                result *= res.op(i).content(x) * res.op(i).unit(x);
@@ -2436,7 +2433,7 @@ static ex factor_multivariate(const ex& poly, const exset& syms)
  */
 struct find_symbols_map : public map_function {
        exset syms;
-       ex operator()(const ex& e)
+       ex operator()(const ex& e) override
        {
                if ( is_a<symbol>(e) ) {
                        syms.insert(e);
@@ -2466,8 +2463,7 @@ static ex factor_sqrfree(const ex& poly)
                        int ld = poly.ldegree(x);
                        ex res = factor_univariate(expand(poly/pow(x, ld)), x);
                        return res * pow(x,ld);
-               }
-               else {
+               } else {
                        ex res = factor_univariate(poly, x);
                        return res;
                }
@@ -2484,7 +2480,7 @@ static ex factor_sqrfree(const ex& poly)
 struct apply_factor_map : public map_function {
        unsigned options;
        apply_factor_map(unsigned options_) : options(options_) { }
-       ex operator()(const ex& e)
+       ex operator()(const ex& e) override
        {
                if ( e.info(info_flags::polynomial) ) {
                        return factor(e, options);
@@ -2494,13 +2490,10 @@ struct apply_factor_map : public map_function {
                        for ( size_t i=0; i<e.nops(); ++i ) {
                                if ( e.op(i).info(info_flags::polynomial) ) {
                                        s1 += e.op(i);
-                               }
-                               else {
+                               } else {
                                        s2 += e.op(i);
                                }
                        }
-                       s1 = s1.eval();
-                       s2 = s2.eval();
                        return factor(s1, options) + s2.map(*this);
                }
                return e.map(*this);
@@ -2532,9 +2525,8 @@ ex factor(const ex& poly, unsigned options)
                return poly;
        }
        lst syms;
-       exset::const_iterator i=findsymbols.syms.begin(), end=findsymbols.syms.end();
-       for ( ; i!=end; ++i ) {
-               syms.append(*i);
+       for (auto & i : findsymbols.syms ) {
+               syms.append(i);
        }
 
        // make poly square free
@@ -2560,17 +2552,14 @@ ex factor(const ex& poly, unsigned options)
                                const ex& base = t.op(0);
                                if ( !is_a<add>(base) ) {
                                        res *= t;
-                               }
-                               else {
+                               } else {
                                        ex f = factor_sqrfree(base);
                                        res *= pow(f, t.op(1));
                                }
-                       }
-                       else if ( is_a<add>(t) ) {
+                       } else if ( is_a<add>(t) ) {
                                ex f = factor_sqrfree(t);
                                res *= f;
-                       }
-                       else {
+                       } else {
                                res *= t;
                        }
                }