[GiNaC-devel] factorization and stuff

[Richard B. Kreckel]

Dear Jens,

Richard B. Kreckel wrote:
> On 2008-08-21, I wrote:
>> Ah, I haven't had my morning coffee yet. So I forgot to include the bug 
>> of the day:
>>  > factor(x);
>> Segmentation fault
> 
> That's fixed now. Thank you!
> 
> Now, I'm getting
>  > factor(expand((x+64*x^4)*(3*x+92*x^4+5*x^2)));
> Segmentation fault
> 
> Is this in any way related with this issue?
>  > factor(x^37+1);
> Not a 32-bit integer: 137438953472

That's fixed now. Thank you!

Now, I'm getting:
 > 
factor(expand((77+102*x^4+27*x+11*x^3+25*x^2)*(85+66*x^4+29*x+57*x^3+92*x^2)));
Not a 32-bit integer: 2955677175

Woops! Sorry for being a nuisance.  ;-)

Well, it's easily fixed with this patch:

diff --git a/ginac/factor.cpp b/ginac/factor.cpp
index 886819a..9081052 100644
--- a/ginac/factor.cpp
+++ b/ginac/factor.cpp
@@ -124,8 +124,8 @@ struct UniPoly
                 // assert: poly is in Z[x]
                 Term t;
                 for ( int i=poly.degree(x); i>=poly.ldegree(x); --i ) {
-                       int coeff = 
ex_to<numeric>(poly.coeff(x,i)).to_int();
-                       if ( coeff ) {
+                       cl_I coeff = 
the<cl_I>(ex_to<numeric>(poly.coeff(x,i)).to_cl_N());
+                       if ( !zerop(coeff) ) {
                                 t.c = R->canonhom(coeff);
                                 if ( !zerop(t.c) ) {
                                         t.exp = i;

This leaves me wondering whether other numeric -> int conversions should 
be treated likewise. What about gamma inside the hensel_univar function? 
I don't know what it is. Can we assume with reasonable certainty that it 
fits the target unsigned int format?

Cheers
   -richy.
-- 
Richard B. Kreckel
<http://www.ginac.de/~kreckel/>