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[ginac.git] / ginac / normal.cpp

diff --git a/ginac/normal.cpp b/ginac/normal.cpp
index a8a1e1eb1bd3f7282418eff3160f2ba1a25114e6..231ef7e868c5be449ecc67ac1cf43f3c63264ffd 100644 (file)
--- a/ginac/normal.cpp
+++ b/ginac/normal.cpp
@@ -6,7 +6,7 @@
  *  computation, square-free factorization and rational function normalization. */
 
 /*
- *  GiNaC Copyright (C) 1999-2016 Johannes Gutenberg University Mainz, Germany
+ *  GiNaC Copyright (C) 1999-2018 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
@@ -146,7 +146,7 @@ struct sym_desc {
        /** Maximum number of terms of leading coefficient of symbol in both polynomials */
        size_t max_lcnops;
 
-       /** Commparison operator for sorting */
+       /** Comparison operator for sorting */
        bool operator<(const sym_desc &x) const
        {
                if (max_deg == x.max_deg)
@@ -270,9 +270,15 @@ static numeric lcm_of_coefficients_denominators(const ex &e)
  *  @param lcm  LCM to multiply in */
 static ex multiply_lcm(const ex &e, const numeric &lcm)
 {
+       if (lcm.is_equal(*_num1_p))
+               // e * 1 -> e;
+               return e;
+
        if (is_exactly_a<mul>(e)) {
+               // (a*b*...)*lcm -> (a*lcma)*(b*lcmb)*...*(lcm/(lcma*lcmb*...))
                size_t num = e.nops();
-               exvector v; v.reserve(num + 1);
+               exvector v;
+               v.reserve(num + 1);
                numeric lcm_accum = *_num1_p;
                for (size_t i=0; i<num; i++) {
                        numeric op_lcm = lcmcoeff(e.op(i), *_num1_p);
@@ -282,18 +288,24 @@ static ex multiply_lcm(const ex &e, const numeric &lcm)
                v.push_back(lcm / lcm_accum);
                return dynallocate<mul>(v);
        } else if (is_exactly_a<add>(e)) {
+               // (a+b+...)*lcm -> a*lcm+b*lcm+...
                size_t num = e.nops();
-               exvector v; v.reserve(num);
+               exvector v;
+               v.reserve(num);
                for (size_t i=0; i<num; i++)
                        v.push_back(multiply_lcm(e.op(i), lcm));
                return dynallocate<add>(v);
        } else if (is_exactly_a<power>(e)) {
-               if (is_a<symbol>(e.op(0)))
-                       return e * lcm;
-               else
-                       return pow(multiply_lcm(e.op(0), lcm.power(ex_to<numeric>(e.op(1)).inverse())), e.op(1));
-       } else
-               return e * lcm;
+               if (!is_a<symbol>(e.op(0))) {
+                       // (b^e)*lcm -> (b*lcm^(1/e))^e if lcm^(1/e) ∈ ℚ (i.e. not a float)
+                       // but not for symbolic b, as evaluation would undo this again
+                       numeric root_of_lcm = lcm.power(ex_to<numeric>(e.op(1)).inverse());
+                       if (root_of_lcm.is_rational())
+                               return pow(multiply_lcm(e.op(0), root_of_lcm), e.op(1));
+               }
+       }
+       // can't recurse down into e
+       return dynallocate<mul>(e, lcm);
 }
 
 
@@ -1536,7 +1548,7 @@ ex gcd(const ex &a, const ex &b, ex *ca, ex *cb, bool check_args, unsigned optio
 
        // The symbol with least degree which is contained in both polynomials
        // is our main variable
-       sym_desc_vec::iterator vari = sym_stats.begin();
+       auto vari = sym_stats.begin();
        while ((vari != sym_stats.end()) && 
               (((vari->ldeg_b == 0) && (vari->deg_b == 0)) ||
                ((vari->ldeg_a == 0) && (vari->deg_a == 0))))
@@ -2386,47 +2398,11 @@ ex ex::to_rational(exmap & repl) const
        return bp->to_rational(repl);
 }
 
-// GiNaC 1.1 compatibility function
-ex ex::to_rational(lst & repl_lst) const
-{
-       // Convert lst to exmap
-       exmap m;
-       for (auto & it : repl_lst)
-               m.insert(std::make_pair(it.op(0), it.op(1)));
-
-       ex ret = bp->to_rational(m);
-
-       // Convert exmap back to lst
-       repl_lst.remove_all();
-       for (auto & it : m)
-               repl_lst.append(it.first == it.second);
-
-       return ret;
-}
-
 ex ex::to_polynomial(exmap & repl) const
 {
        return bp->to_polynomial(repl);
 }
 
-// GiNaC 1.1 compatibility function
-ex ex::to_polynomial(lst & repl_lst) const
-{
-       // Convert lst to exmap
-       exmap m;
-       for (auto & it : repl_lst)
-               m.insert(std::make_pair(it.op(0), it.op(1)));
-
-       ex ret = bp->to_polynomial(m);
-
-       // Convert exmap back to lst
-       repl_lst.remove_all();
-       for (auto & it : m)
-               repl_lst.append(it.first == it.second);
-
-       return ret;
-}
-
 /** Default implementation of ex::to_rational(). This replaces the object with
  *  a temporary symbol. */
 ex basic::to_rational(exmap & repl) const