giac does not do Groebner bases in rings with more than 15 variables

dimpase commented 1 year ago

Is there an existing issue for this?

[X] I have searched the existing issues for a bug report that matches the one I want to file, without success.

Did you read the documentation and troubleshoot guide?

[X] I have read the documentation and troubleshoot guide

Environment

everywhere

Steps To Reproduce

check giac's src/cocoa.h :

// GIAC_64VARS is currently compatible with GROEBNER_VARS 15 only
// special code for polynomial up to 11 variables (max deg<32768) 
//#define GROEBNER_VARS 11
#define GROEBNER_VARS 15

and lines 490-500 of giac's src/cocoa.cc

Expected Behavior

this should be documented, and checked in our interface src/sage/libs/giac/__init__.py

Actual Behavior

it's not

Additional Information

@parisseb

reported by Brent Baccala on sage-develop.

parisseb commented 1 year ago

Actually giac does Groebner bases in rings with more than 15 variables, it's just less efficient because the most efficient data representation works only up to 15 variables. Then there are little less efficient data representation up to 32 and then 64 variables.

dimpase commented 1 year ago

So the maximum is 64 variables? In the Brent's report 67 variables were used, and it didn't work.

parisseb commented 1 year ago

Hum, I don't remember, I'll check when I'll have more time.

sagemath / sage