Converting terms into primitive polynomials optimized [A.Sheplyakov]

[ginac.git] / ginac / mul.cpp

diff --git a/ginac/mul.cpp b/ginac/mul.cpp
index dd96a70fafdb15114985a1dce12d6d4aeba3569b..9ed27c6c4bf3f4c7435674de9138bb4aa16d76fc 100644 (file)
--- a/ginac/mul.cpp
+++ b/ginac/mul.cpp
@@ -34,6 +34,7 @@
 #include "lst.h"
 #include "archive.h"
 #include "utils.h"
+#include "compiler.h"
 
 namespace GiNaC {
 
@@ -315,7 +316,11 @@ int mul::degree(const ex & s) const
        epvector::const_iterator i = seq.begin(), end = seq.end();
        while (i != end) {
                if (ex_to<numeric>(i->coeff).is_integer())
-                       deg_sum += i->rest.degree(s) * ex_to<numeric>(i->coeff).to_int();
+                       deg_sum += recombine_pair_to_ex(*i).degree(s);
+               else {
+                       if (i->rest.has(s))
+                               throw std::runtime_error("mul::degree() undefined degree because of non-integer exponent");
+               }
                ++i;
        }
        return deg_sum;
@@ -328,7 +333,11 @@ int mul::ldegree(const ex & s) const
        epvector::const_iterator i = seq.begin(), end = seq.end();
        while (i != end) {
                if (ex_to<numeric>(i->coeff).is_integer())
-                       deg_sum += i->rest.ldegree(s) * ex_to<numeric>(i->coeff).to_int();
+                       deg_sum += recombine_pair_to_ex(*i).ldegree(s);
+               else {
+                       if (i->rest.has(s))
+                               throw std::runtime_error("mul::ldegree() undefined degree because of non-integer exponent");
+               }
                ++i;
        }
        return deg_sum;
@@ -414,7 +423,7 @@ ex mul::eval(int level) const
                return *this;
        }
        
-       int seq_size = seq.size();
+       size_t seq_size = seq.size();
        if (overall_coeff.is_zero()) {
                // *(...,x;0) -> 0
                return _ex0;
@@ -438,9 +447,81 @@ ex mul::eval(int level) const
                }
                return (new add(distrseq,
                                ex_to<numeric>(addref.overall_coeff).
-                               mul_dyn(ex_to<numeric>(overall_coeff))))
-                     ->setflag(status_flags::dynallocated | status_flags::evaluated);
+                               mul_dyn(ex_to<numeric>(overall_coeff)))
+                      )->setflag(status_flags::dynallocated | status_flags::evaluated);
+       } else if ((seq_size >= 2) && (! (flags & status_flags::expanded))) {
+               // Strip the content and the unit part from each term. Thus
+               // things like (-x+a)*(3*x-3*a) automagically turn into - 3*(x-a)2
+
+               epvector::const_iterator last = seq.end();
+               epvector::const_iterator i = seq.begin();
+               epvector::const_iterator j = seq.begin();
+               std::auto_ptr<epvector> s(new epvector);
+               numeric oc = *_num1_p;
+               bool something_changed = false;
+               while (i!=last) {
+                       if (likely(! (is_a<add>(i->rest) && i->coeff.is_equal(_ex1)))) {
+                               // power::eval has such a rule, no need to handle powers here
+                               ++i;
+                               continue;
+                       }
+
+                       // XXX: What is the best way to check if the polynomial is a primitive? 
+                       numeric c = i->rest.integer_content();
+                       const numeric& lead_coeff =
+                               ex_to<numeric>(ex_to<add>(i->rest).seq.begin()->coeff).div_dyn(c);
+                       const bool canonicalizable = lead_coeff.is_integer();
+
+                       // XXX: The main variable is chosen in a random way, so this code 
+                       // does NOT transform the term into the canonical form (thus, in some
+                       // very unlucky event it can even loop forever). Hopefully the main
+                       // variable will be the same for all terms in *this
+                       const bool unit_normal = lead_coeff.is_pos_integer();
+                       if (likely((c == *_num1_p) && ((! canonicalizable) || unit_normal))) {
+                               ++i;
+                               continue;
+                       }
+
+                       if (! something_changed) {
+                               s->reserve(seq_size);
+                               something_changed = true;
+                       }
+
+                       while ((j!=i) && (j!=last)) {
+                               s->push_back(*j);
+                               ++j;
+                       }
+
+                       if (! unit_normal)
+                               c = c.mul(*_num_1_p);
+
+                       oc = oc.mul(c);
+
+                       // divide add by the number in place to save at least 2 .eval() calls
+                       const add& addref = ex_to<add>(i->rest);
+                       add* primitive = new add(addref);
+                       primitive->setflag(status_flags::dynallocated);
+                       primitive->clearflag(status_flags::hash_calculated);
+                       primitive->overall_coeff = ex_to<numeric>(primitive->overall_coeff).div_dyn(c);
+                       for (epvector::iterator ai = primitive->seq.begin();
+                                       ai != primitive->seq.end(); ++ai)
+                               ai->coeff = ex_to<numeric>(ai->coeff).div_dyn(c);
+                       
+                       s->push_back(expair(*primitive, _ex1));
+
+                       ++i;
+                       ++j;
+               }
+               if (something_changed) {
+                       while (j!=last) {
+                               s->push_back(*j);
+                               ++j;
+                       }
+                       return (new mul(s, ex_to<numeric>(overall_coeff).mul_dyn(oc))
+                              )->setflag(status_flags::dynallocated);
+               }
        }
+
        return this->hold();
 }