gr, hgr, gr_mod, dgr

gr(plist,vlist,order)

hgr(plist,vlist,order)

gr_mod(plist,vlist,order,p)

dgr(plist,vlist,order,procs)

:: Groebner basis computation

return

list

plist, vlist, procs

list

order

number, list or matrix

p

prime less than 2^27

• These functions are defined in `gr' in the standard library directory.
• They compute a Groebner basis of a polynomial list plist with respect to the variable order vlist and the order type order. gr() and hgr() compute a Groebner basis over the rationals and gr_mod computes over GF(p).
• Variables not included in vlist are regarded as included in the ground field.
• gr() uses trace-lifting (an improvement by modular computation) and sugar strategy. hgr() uses trace-lifting and a cured sugar strategy by using homogenization.
• dgr() executes gr(), dgr() simultaneously on two process in a child process list procs and returns the result obtained first. The results returned from both the process should be equal, but it is not known in advance which method is faster. Therefore this function is useful to reduce the actual elapsed time.
• The CPU time shown after an exection of dgr() indicates that of the master process, and most of the time corresponds to the time for communication.

[0] load("gr")$
[64] load("cyclic")$
[74] G=gr(cyclic(5),[c0,c1,c2,c3,c4],2);
[c4^15+122*c4^10-122*c4^5-1,...]
[75] GM=gr_mod(cyclic(5),[c0,c1,c2,c3,c4],2,31991)$
24628*c4^15+29453*c4^10+2538*c4^5+7363
[76] (G[0]*24628-GM[0])%31991;
0

References

section dp_gr_main, dp_gr_mod_main, section dp_ord.

Go to the first, previous, next, last section, table of contents.