Several fixes for Random on long lists in 64-bit GAP #781

frankluebeck · 2016-05-05T09:24:04Z

removes the kernel function RandomListMT
adjusts RandomList to documentation
fixes several problems by using new RandomList instead of RANDOM_LIST
ensures that RANDOM_LIST is only called for lists of length < 2^28
introduces a simple scheme for test code that runs differently on 32bit and 64bit GAP
adds some test code for Random on lists

As reported by Stefan Kohl, RandomListMT did not work as expected in 64-bit GAP on lists of length >= 2^28. Kernel function removed, corresponding GAP function now uses Random(1,Length(list)).

RANDOM_LIST (compiled function from lib/random.g) does not work as expected in 64-bit GAP on list of length >= 2^28 (it only returns positions which are equal mod 2^28). RandomList did not use the Mersenne twister as is explicitly documented (but was synonym to RANDOM_LIST). - Now RandomList works as documented. - RandomList is used in several places of the library instead of RANDOM_LIST. - Functions for the GlobalRandomSource and GAPRandomSource now use RANDOM_LIST only for lists of length < 2^28.

Introduced two directories for code that behaves differently in 32-bit GAP and 64-bit GAP. Only one is used in tst/teststandard.g depending on the current GAP.

markuspf · 2016-05-05T11:29:30Z

@james-d-mitchell does the partial permutations test code rely on some (previously wrong?) behaviour of Random?

ChrisJefferson · 2016-05-05T11:43:22Z

This all looks good and all correct to me, better than my previous pull request.

james-d-mitchell · 2016-05-09T14:21:47Z

@markuspf I don't think so, but who knows. I plan to rewrite those tests when I get some time!

markuspf · 2016-05-09T14:26:34Z

I suppose we can just use the usual kludge of updating the test for the time being...

olexandr-konovalov · 2016-05-10T11:27:48Z

yes, it's only two lines in testinstall/pperm.tst that need updating. Let's merge this and fix them.

olexandr-konovalov · 2016-05-10T16:32:00Z

This certainly leads to diffs in manual examples - I will update these within a couple of days:

============================================================
########> Diff in [ "./../../lib/random.gd", 114, 123 ]
# Input is:
List([1..10],i->Random(Integers));
# Expected output:
[ -1, -3, -2, 1, -2, -1, 0, 1, 0, 1 ]
# But found:
[ 2, -1, -2, -1, -1, 1, -4, 1, 0, -1 ]
########
########> Diff in [ "./../../lib/random.gd", 114, 123 ]
# Input is:
List([1..10],i->Random(Integers));
# Expected output:
[ -1, 0, 2, 0, 4, -1, -3, 1, -4, -1 ]
# But found:
[ -1, -1, 1, -1, 1, -2, -1, -2, 0, -1 ]
########
########> Diff in [ "./../../lib/random.gd", 114, 123 ]
# Input is:
List([1..10],i->Random(Integers));
# Expected output:
[ -1, -3, -2, 1, -2, -1, 0, 1, 0, 1 ]
# But found:
[ 2, -1, -2, -1, -1, 1, -4, 1, 0, -1 ]
########
########> Diff in [ "./../../lib/random.gd", 208, 221 ]
# Input is:
n := Random(rs1, 1, 2^220);
# Expected output:
1598617776705343302477918831699169150767442847525442557699717518961
# But found:
1077726777923092117987668044202944212469136000816111066409337432400
########
########> Diff in [ "./../../lib/list.gd", 1426, 1439 ]
# Input is:
m := Shuffle(ShallowCopy(l));
# Expected output:
[ 15, 13, 3, 19, 8, 11, 14, 7, 16, 4, 17, 18, 5, 1, 10, 6, 2, 9, 12, 
 20 ]
# But found:
[ 8, 13, 1, 3, 20, 15, 4, 7, 5, 18, 6, 12, 16, 11, 2, 10, 19, 17, 9, 
 14 ]
########
########> Diff in [ "./../../lib/list.gd", 1426, 1439 ]
# Input is:
l;
# Expected output:
[ 3, 4, 18, 13, 10, 7, 9, 8, 14, 17, 16, 6, 19, 12, 1, 11, 20, 2, 15, 
 5 ]
# But found:
[ 19, 5, 7, 20, 16, 1, 10, 15, 12, 11, 13, 2, 14, 3, 4, 17, 6, 8, 9, 
 18 ]
########
########> Diff in [ "./../../lib/matrix.gd", 1628, 1635 ]
# Input is:
m := RandomInvertibleMat(4);
# Expected output:
[ [ 1, -2, -1, 0 ], [ 1, 0, 1, -1 ], [ 0, 2, 0, 4 ], 
 [ -1, -3, 1, -4 ] ]
# But found:
[ [ -4, 1, 0, -1 ], [ -1, -1, 1, -1 ], [ 1, -2, -1, -2 ], 
 [ 0, -1, 2, -2 ] ]
########
########> Diff in [ "./../../lib/matrix.gd", 1628, 1635 ]
# Input is:
m^-1;
# Expected output:
[ [ 1/4, 1/2, -1/8, -1/4 ], [ -1/3, 0, -1/3, -1/3 ], 
 [ -1/12, 1/2, 13/24, 5/12 ], [ 1/6, 0, 5/12, 1/6 ] ]
# But found:
[ [ -1/8, -11/24, 1/24, 1/4 ], [ 1/4, -13/12, -1/12, 1/2 ], 
 [ -1/8, 5/24, -7/24, 1/4 ], [ -1/4, 3/4, -1/4, -1/2 ] ]
########
########> Diff in [ "./../../lib/matrix.gd", 1677, 1682 ]
# Input is:
m := RandomUnimodularMat(3);
# Expected output:
[ [ 1, 0, 0 ], [ 156, -39, -25 ], [ -100, 25, 16 ] ]
# But found:
[ [ -5, 1, 0 ], [ 12, -2, -1 ], [ -14, 3, 0 ] ]
########
########> Diff in [ "./../../lib/matrix.gd", 1677, 1682 ]
# Input is:
m^-1;
# Expected output:
[ [ 1, 0, 0 ], [ 4, 16, 25 ], [ 0, -25, -39 ] ]
# But found:
[ [ -3, 0, 1 ], [ -14, 0, 5 ], [ -8, -1, 2 ] ]
########
########> Diff in [ "./../../lib/coll.gd", 1621, 1631 ]
# Input is:
Random([1..6]);
# Expected output:
1
# But found:
6
########
########> Diff in [ "./../../lib/coll.gd", 1621, 1631 ]
# Input is:
g:= Group( (1,2,3) );;  Random( g );  Random( g );
# Expected output:
(1,3,2)
(1,2,3)
# But found:
(1,3,2)
()
########
########> Diff in [ "./../../lib/coll.gd", 1621, 1631 ]
# Input is:
Random(Rationals);
# Expected output:
-2
# But found:
-4
########
########> Diff in [ "./../../lib/straight.gd", 631, 645 ]
# Input is:
Random(g);
# Expected output:
<
[ [ 1, -1, 2, -1, 1, 1, 2, -1, 1, -1, 2, 1, 1, 1, 2, 1, 1, -1, 2, 2, 
     1, 1 ], 
 [ 3, -2, 2, -2, 1, -1, 2, -2, 1, 1, 2, -1, 1, -1, 2, -2, 1, 1, 2, 
     -1, 1, -1, 2, -1, 1, 1, 2, 1, 1, -1, 2, 1, 1, 1 ] ]>
# But found:
<
[ [ 1, -1, 2, -1, 1, 1, 2, -1, 1, -1, 2, 1, 1, 1, 2, 1, 1, -1, 2, 2, 
     1, 1 ], [ 3, -2, 2, -2 ], 
 [ 4, 1, 1, -1, 2, -2, 1, 1, 2, -1, 4, 1 ] ]|(1,3)>
########
########> Diff in [ "./../../lib/grp.gd", 3166, 3170 ]
# Input is:
s:=SubnormalSeries(g,Group((1,2)(3,4)));
# Expected output:
[ Group([ (1,2,3,4), (1,2) ]), Group([ (1,2)(3,4), (1,3)(2,4) ]), 
Group([ (1,2)(3,4) ]) ]
# But found:
[ Group([ (1,2,3,4), (1,2) ]), Group([ (1,2)(3,4), (1,4)(2,3) ]), 
 Group([ (1,2)(3,4) ]) ]
########
########> Diff in [ "./../../lib/teaching.g", 195, 200 ]
# Input is:
AllHomomorphismClasses(SymmetricGroup(4),SymmetricGroup(3)); 
# Expected output:
[ [ (1,3,4,2), (1,2,4) ] -> [ (), () ], 
 [ (1,3,4,2), (1,2,4) ] -> [ (1,2), () ], 
 [ (1,3,4,2), (1,2,4) ] -> [ (2,3), (1,2,3) ] ]
# But found:
[ [ (1,3,4,2), (1,3,4) ] -> [ (), () ], 
 [ (1,3,4,2), (1,3,4) ] -> [ (1,2), () ], 
 [ (1,3,4,2), (1,3,4) ] -> [ (2,3), (1,2,3) ] ]
########
########> Diff in [ "./../../lib/morpheus.gd", 504, 511 ]
# Input is:
quo:=GQuotients(g,h);
# Expected output:
[ [ (1,2,4,3), (1,2,3) ] -> [ (2,3), (1,2,3) ] ]
# But found:
[ [ (1,3,2,4), (1,3,2) ] -> [ (2,3), (1,2,3) ] ]
########
########> Diff in [ "./grpfp.xml", 266, 279 ]
# Input is:
h := IsomorphismPermGroup( g );
# Expected output:
[ a, b ] -> [ (1,2)(4,5), (2,3,4) ]
# But found:
[ a, b ] -> [ (2,4)(5,6), (1,2,3)(4,5,6) ]
########
########> Diff in [ "./../../lib/grp.gd", 4068, 4077 ]
# Input is:
RelatorsOfFpGroup( fp );
# Expected output:
[ F1^2, F2^5, (F2^-1*F1)^4, (F2^-1*F1*F2*F1)^3, (F2^2*F1*F2^-2*F1)^2 ]
# But found:
[ F1^2, F2^5, (F2^-1*F1)^4, (F2*F1*F2^-1*F1)^3, (F2*F1*F2^-2*F1*F2)^2 
]
########
########> Diff in [ "./../../lib/grp.gd", 4097, 4106 ]
# Input is:
iso := IsomorphismFpGroupByGenerators( M12, gens );;
# Expected output:
#I  the image group has 3 gens and 23 rels of total length 628
# But found:
#I  the image group has 3 gens and 18 rels of total length 337
########
########> Diff in [ "./../../lib/grp.gd", 4097, 4106 ]
# Input is:
iso := IsomorphismFpGroupByGenerators( M12, gens );;
# Expected output:
#I  the image group has 3 gens and 23 rels of total length 569
# But found:
#I  the image group has 3 gens and 19 rels of total length 493
########
########> Diff in [ "./../../lib/grp.gd", 4148, 4155 ]
# Input is:
iso := IsomorphismFpGroupByGenerators( M12, gens : 
                                         method := "fast" );;
# Expected output:
#I  the image group has 3 gens and 150 rels of total length 3336
# But found:
#I  the image group has 3 gens and 154 rels of total length 3389
########
########> Diff in [ "./../../lib/grp.gd", 4167, 4189 ]
# Input is:
iso := IsomorphismFpGroupByGenerators( G, gens );;
# Expected output:
#I  the image group has 2 gens and 10 rels of total length 128
# But found:
#I  the image group has 2 gens and 9 rels of total length 94
########
########> Diff in [ "./xtndxmpl.xml", 846, 860 ]
# Input is:
gens:= GeneratorsOfGroup( syl3 );
# Expected output:
[ [ [ ( 15 mod 16 ), ( 5 mod 16 ) ], [ ( 3 mod 16 ), ( 0 mod 16 ) ] ] 
]
# But found:
[ [ [ ( 1 mod 16 ), ( 7 mod 16 ) ], [ ( 11 mod 16 ), ( 14 mod 16 ) ] 
    ] ]
########
=========OUTPUT END: testmanuals with autoloaded packages=========

olexandr-konovalov · 2016-05-31T14:23:32Z

This PR has been made into master but then cherry-picked onto stable-4.8. That's why it belongs to GAP 4.8.4 milestone.

frankluebeck added 3 commits May 5, 2016 09:45

Remove RandomListMT

b7fe204

As reported by Stefan Kohl, RandomListMT did not work as expected in 64-bit GAP on lists of length >= 2^28. Kernel function removed, corresponding GAP function now uses Random(1,Length(list)).

Some tests for Random on lists.

6473f24

Introduced two directories for code that behaves differently in 32-bit GAP and 64-bit GAP. Only one is used in tst/teststandard.g depending on the current GAP.

This was referenced May 5, 2016

Bug in Random for ranges? #772

Closed

Fix random element selection from long lists #778

Closed

olexandr-konovalov mentioned this pull request May 10, 2016

Several fixes for Random on long lists in 64-bit GAP #780

Closed

markuspf merged commit 6c9b41d into gap-system:master May 10, 2016

hulpke mentioned this pull request May 23, 2016

Regression in ConstructAllGroups(2916) between stable-4.8 and master #798

Closed

olexandr-konovalov added this to the GAP 4.8.4 milestone May 31, 2016

fingolfin mentioned this pull request Sep 7, 2017

Release notes for GAP 4.9 #1699

Closed

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Several fixes for Random on long lists in 64-bit GAP #781

Several fixes for Random on long lists in 64-bit GAP #781

frankluebeck commented May 5, 2016

markuspf commented May 5, 2016

ChrisJefferson commented May 5, 2016

james-d-mitchell commented May 9, 2016

markuspf commented May 9, 2016

olexandr-konovalov commented May 10, 2016

olexandr-konovalov commented May 10, 2016

olexandr-konovalov commented May 31, 2016

Several fixes for Random on long lists in 64-bit GAP #781

Several fixes for Random on long lists in 64-bit GAP #781

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frankluebeck commented May 5, 2016

markuspf commented May 5, 2016

ChrisJefferson commented May 5, 2016

james-d-mitchell commented May 9, 2016

markuspf commented May 9, 2016

olexandr-konovalov commented May 10, 2016

olexandr-konovalov commented May 10, 2016

olexandr-konovalov commented May 31, 2016