Converting terms into primitive polynomials optimized [A.Sheplyakov]

[ginac.git] / ginac / power.cpp

diff --git a/ginac/power.cpp b/ginac/power.cpp
index fb5e351e7390204dbe6b024f5cc2f8a80c67625b..faa0d05cc61eb156e0554a9b787b6db4ff8a7e19 100644 (file)
--- a/ginac/power.cpp
+++ b/ginac/power.cpp
@@ -41,6 +41,7 @@
 #include "archive.h"
 #include "utils.h"
 #include "relational.h"
+#include "compiler.h"
 
 namespace GiNaC {
 
@@ -231,6 +232,8 @@ bool power::info(unsigned inf) const
                case info_flags::algebraic:
                        return !exponent.info(info_flags::integer) ||
                               basis.info(inf);
+               case info_flags::expanded:
+                       return (flags & status_flags::expanded);
        }
        return inherited::info(inf);
 }
@@ -467,8 +470,9 @@ ex power::eval(int level) const
                        if (is_exactly_a<numeric>(sub_exponent)) {
                                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_p)).is_negative())
+                               if (num_exponent->is_integer() || (abs(num_sub_exponent) - (*_num1_p)).is_negative()) {
                                        return power(sub_basis,num_sub_exponent.mul(*num_exponent));
+                               }
                        }
                }
        
@@ -476,7 +480,35 @@ ex power::eval(int level) const
                if (num_exponent->is_integer() && is_exactly_a<mul>(ebasis)) {
                        return expand_mul(ex_to<mul>(ebasis), *num_exponent, 0);
                }
-       
+
+               // (2*x + 6*y)^(-4) -> 1/16*(x + 3*y)^(-4)
+               if (num_exponent->is_integer() && is_exactly_a<add>(ebasis)) {
+                       numeric icont = ebasis.integer_content();
+                       const numeric& lead_coeff = 
+                               ex_to<numeric>(ex_to<add>(ebasis).seq.begin()->coeff).div_dyn(icont);
+
+                       const bool canonicalizable = lead_coeff.is_integer();
+                       const bool unit_normal = lead_coeff.is_pos_integer();
+                       if (canonicalizable && (! unit_normal))
+                               icont = icont.mul(*_num_1_p);
+                       
+                       if (canonicalizable && (icont != *_num1_p)) {
+                               const add& addref = ex_to<add>(ebasis);
+                               add* addp = new add(addref);
+                               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);
+
+                               const numeric c = icont.power(*num_exponent);
+                               if (likely(c != *_num1_p))
+                                       return (new mul(power(*addp, *num_exponent), c))->setflag(status_flags::dynallocated);
+                               else
+                                       return power(*addp, *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)
                if (is_exactly_a<mul>(ebasis)) {