id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,work_issues,upstream,reviewer,author,merged,dependencies,stopgaps 7424,inconsistency between constructors SL and PSL,AlexGhitza,joyner,"Probably because these are implemented as different classes (matrix group versus permutation group), the constructors for {{{SL}}} and {{{PSL}}} have slightly different behaviour. In particular, {{{PSL}}} does not take a field argument, and the error message it gives is misleading. We should just make it behave exactly like {{{SL}}}: {{{ [ghitza@artin ~]$ sage ---------------------------------------------------------------------- | Sage Version 4.2, Release Date: 2009-10-24 | | Type notebook() for the GUI, and license() for information. | ---------------------------------------------------------------------- sage: SL(2, 7) Special Linear Group of degree 2 over Finite Field of size 7 sage: SL(2, GF(7)) Special Linear Group of degree 2 over Finite Field of size 7 sage: PSL(2, 7) Permutation Group with generators [(3,7,5)(4,8,6), (1,2,6)(3,4,8)] sage: PSL(2, GF(7)) --------------------------------------------------------------------------- RuntimeError Traceback (most recent call last) /home/ghitza/.sage/temp/artin/31630/_home_ghitza__sage_init_sage_0.py in () /home/ghitza/sage-stable/local/lib/python2.6/site-packages/sage/groups/perm_gps/permgroup_named.pyc in __init__(self, n, q, name) 645 else: 646 id = 'PSL(%s,%s)'%(n,q) --> 647 PermutationGroup_generic.__init__(self, gap_group=id) 648 self._q = q 649 self._base_ring = GF(q, name=name) /home/ghitza/sage-stable/local/lib/python2.6/site-packages/sage/groups/perm_gps/permgroup.pyc in __init__(self, gens, gap_group, canonicalize) 334 if gens is None: 335 self._gap_string = gap_group if isinstance(gap_group, str) else str(gap_group) --> 336 self._gens = self._gens_from_gap() 337 return 338 /home/ghitza/sage-stable/local/lib/python2.6/site-packages/sage/groups/perm_gps/permgroup.pyc in _gens_from_gap(self) 363 gens = self._gap_().GeneratorsOfGroup() 364 except TypeError, s: --> 365 raise RuntimeError, ""(It might be necessary to install the database_gap optional Sage package, if you haven't already.)\n%s""%s 366 gens = [self._element_class()(gens[n],self, check=False) 367 for n in range(1, int(gens.Length())+1)] RuntimeError: (It might be necessary to install the database_gap optional Sage package, if you haven't already.) Gap produced error output Variable: 'Finite' must have a value Syntax error: ) expected $sage3:=PSL(2,Finite Field of size 7);; ^ executing $sage3:=PSL(2,Finite Field of size 7);; }}} ",defect,new,minor,sage-5.11,group theory,,,,,,,,,,