[PATCH] Improve normalisation of negative exponents.

[ginac.git] / ginac / normal.cpp

diff --git a/ginac/normal.cpp b/ginac/normal.cpp
index ce606f0809411286cfef98e0f93df9b4ad5ac7ae..818aa808159a1789c7d577a3f3e7f6b4a6e0ea36 100644 (file)
--- a/ginac/normal.cpp
+++ b/ginac/normal.cpp
@@ -2196,14 +2196,18 @@ ex basic::normal(exmap & repl, exmap & rev_lookup, lst & modifier) const
 
        normal_map_function map_normal;
        int nmod = modifier.nops(); // To watch new modifiers to the replacement list
 
        normal_map_function map_normal;
        int nmod = modifier.nops(); // To watch new modifiers to the replacement list

-       lst result = dynallocate<lst>({replace_with_symbol(map(map_normal), repl, rev_lookup, modifier), _ex1});
+       ex result = replace_with_symbol(map(map_normal), repl, rev_lookup, modifier);

        for (int imod = nmod; imod < modifier.nops(); ++imod) {
                exmap this_repl;
                this_repl.insert(std::make_pair(modifier.op(imod).op(0), modifier.op(imod).op(1)));
        for (int imod = nmod; imod < modifier.nops(); ++imod) {
                exmap this_repl;
                this_repl.insert(std::make_pair(modifier.op(imod).op(0), modifier.op(imod).op(1)));

-               result = ex_to<lst>(result.subs(this_repl, subs_options::no_pattern));
+               result = result.subs(this_repl, subs_options::no_pattern);

        }
 
        }
 

-       return result;
+       // Sometimes we may obtain negative powers, they need to be placed to denominator
+       if (is_a<power>(result) && result.op(1).info(info_flags::negative))
+               return dynallocate<lst>({_ex1, power(result.op(0), -result.op(1))});
+       else
+               return dynallocate<lst>({result, _ex1});

 }
 
 
 }