primdecSY (but not primdecGTZ) gives wrong result

[peterj@…]

ring rr = 0,(a,c,d,e,f,g,b),dp; /* primdecGTZ is MUCH slower if b is in usual position */ LIB "primdec.lib";

ideal fails = 3a2-3a+1, 3b2+3ab-3b-3a+2, 3eg+3a-1, 3cf+3a-1, ef2-d2g, cd2-e2f;

ideal OK = 3a2-3a+1, 3b2+3ab-3b-3a+2, cf-eg, /* the only change */ 3cf+3a-1, ef2-d2g, cd2-e2f;

primdecSY(fails); /* 1 factor ?!*/ primdecGTZ(fails); /* 2 prime factors; is correct. */

/* Using Singular 3-1-5 under Ubuntu 12.04. */ /* Repeated attempts to upgrade have failed */

[hannes]

This is a problem of the missing update (4-0-2 works correctly here, may be fixed long ago). To update:

• apt-get remove singular
• apt-get autoremove
• remove the entry ​http://www.mathematik.uni-kl.de/~mschulze.... from /etc/apt/sources.list
• install a new version of singular following the instructions at ​http://www.singular.uni-kl.de/index.php/singular-download/110.html