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

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merged 3 commits into from
May 10, 2016
Merged

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

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b7fe204
Remove RandomListMT
frankluebeck May 5, 2016
86e8092
Fix RandomList and use of RANDOM_LIST
frankluebeck May 5, 2016
6473f24
Some tests for Random on lists.
frankluebeck May 5, 2016
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2 changes: 1 addition & 1 deletion lib/coll.gd
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Original file line number Diff line number Diff line change
Expand Up @@ -1694,7 +1694,7 @@ DeclareOperation( "Random", [ IS_INT, IS_INT ] );
## </ManSection>
## <#/GAPDoc>
##
DeclareSynonym( "RandomList", RANDOM_LIST);
DeclareGlobalFunction( "RandomList" );


#############################################################################
Expand Down
11 changes: 7 additions & 4 deletions lib/coll.gi
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Expand Up @@ -242,11 +242,15 @@ InstallMethod( RepresentativeSmallest,
##
## The default function for random selection in a finite collection computes
## an enumerator of <C> and selects a random element of this list using the
## function `RANDOM_LIST', which is a pseudo random number generator.
## function `RandomList', which is a pseudo random number generator.
##
DeclareGlobalVariable( "GlobalMersenneTwister" );
InstallGlobalFunction( RandomList, function(list)
return list[Random(GlobalMersenneTwister, 1, Length(list))];
end );
InstallMethod( Random, "for a (finite) collection",
[ IsCollection and IsFinite ],
C -> RANDOM_LIST( Enumerator( C ) ) );
C -> RandomList( Enumerator( C ) ) );

RedispatchOnCondition(Random,true,[IsCollection],[IsFinite],0);

Expand All @@ -258,8 +262,7 @@ RedispatchOnCondition(Random,true,[IsCollection],[IsFinite],0);
InstallMethod( PseudoRandom,
"for an internal list",
[ IsList and IsInternalRep ], 100,
#T ?
RANDOM_LIST );
RandomList );


#############################################################################
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4 changes: 2 additions & 2 deletions lib/list.gi
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Expand Up @@ -457,14 +457,14 @@ InstallOtherMethod(
InstallOtherMethod( Random,
"for a dense small list",
[ IsList and IsDenseList and IsSmallList ],
RANDOM_LIST );
RandomList );

InstallOtherMethod( Random,
"for a dense (small) list",
[ IsList and IsDenseList ],
function( list )
if IsSmallList( list ) then
return RANDOM_LIST( list );
return RandomList( list );
else
TryNextMethod();
fi;
Expand Down
3 changes: 2 additions & 1 deletion lib/random.gd
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Expand Up @@ -187,7 +187,8 @@ DeclareCategory("IsGAPRandomSource", IsRandomSource);
DeclareCategory("IsMersenneTwister", IsRandomSource);

DeclareGlobalVariable( "GlobalRandomSource" );
DeclareGlobalVariable( "GlobalMersenneTwister" );
# this declaration is in coll.gi because it is needed for RandomList
# DeclareGlobalVariable( "GlobalMersenneTwister" );

#############################################################################
##
Expand Down
29 changes: 19 additions & 10 deletions lib/random.gi
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Expand Up @@ -93,7 +93,11 @@ InstallMethod(Reset, [IsGlobalRandomSource, IsObject], function(rs, seed)
end);

InstallMethod(Random, [IsGlobalRandomSource, IsList], function(rs, l)
return RANDOM_LIST(l);
if Length(l) < 2^28 then
return RANDOM_LIST(l);
else
return l[Random(rs, 1, Length(l))];
fi;
end);

############################################################################
Expand Down Expand Up @@ -137,12 +141,16 @@ end);

InstallMethod(Random, [IsGAPRandomSource, IsList], function(rs, list)
local rx, rn;
# we need to repeat the code of RANDOM_LIST
rx := rs!.R_X;
rn := rs!.R_N mod 55 + 1;
rs!.R_N := rn;
rx[rn] := (rx[rn] + rx[(rn+30) mod 55+1]) mod R_228;
return list[ QUO_INT( rx[rn] * LEN_LIST(list), R_228 ) + 1 ];
if Length(list) < 2^28 then
# we need to repeat the code of RANDOM_LIST
rx := rs!.R_X;
rn := rs!.R_N mod 55 + 1;
rs!.R_N := rn;
rx[rn] := (rx[rn] + rx[(rn+30) mod 55+1]) mod R_228;
return list[ QUO_INT( rx[rn] * LEN_LIST(list), R_228 ) + 1 ];
else
return list[Random(rs, 1, Length(list))];
fi;
end);


Expand Down Expand Up @@ -190,7 +198,7 @@ InstallMethod(Reset, [IsMersenneTwister, IsObject], function(rs, seed)
end);

InstallMethod(Random, [IsMersenneTwister, IsList], function(rs, list)
return RandomListMT(rs!.state, list);
return list[Random(rs, 1, Length(list))];
end);

InstallMethod(Random, [IsMersenneTwister, IsInt, IsInt], function(rs, a, b)
Expand All @@ -215,8 +223,9 @@ InstallValue(GlobalMersenneTwister, RandomSource(IsMersenneTwister, "1"));
# default random method for lists and pairs of integers using the Mersenne
# twister
InstallMethod( Random, "for an internal list",
[ IsList and IsInternalRep ], 100,
function(l) return Random(GlobalMersenneTwister, l); end );
[ IsList and IsInternalRep ], 100, function(l)
return l[Random(GlobalMersenneTwister, 1, Length(l))];
end );

InstallMethod( Random,
"for two integers",
Expand Down
33 changes: 0 additions & 33 deletions src/intfuncs.c
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Expand Up @@ -202,36 +202,6 @@ UInt4 nextrandMT_int32(UInt4* mt)
return y;
}


Obj FuncRandomListMT(Obj self, Obj mtstr, Obj list)
{
Int len, a, lg;
UInt4 *mt;
while ((! IsStringConv(mtstr)) || GET_LEN_STRING(mtstr) < 2500) {
mtstr = ErrorReturnObj(
"<mtstr> must be a string with at least 2500 characters, ",
0L, 0L,
"you can replace <mtstr> via 'return <mtstr>;'" );
}
while (! IS_LIST(list)) {
list = ErrorReturnObj(
"<list> must be a list, not a %s",
(Int)TNAM_OBJ(list), 0L,
"you can replace <list> via 'return <list>;'" );
}
len = LEN_LIST(list);
if (len == 0) return Fail;
mt = (UInt4*) CHARS_STRING(mtstr);
lg = 31 - CLog2Int(len);
for (a = nextrandMT_int32(mt) >> lg;
a >= len;
a = nextrandMT_int32(mt) >> lg
);
return ELM_LIST(list, a+1);
}



/****************************************************************************
**
*F FuncHASHKEY_BAG(<self>,<obj>,<seed>,<offset>,<maxlen>)
Expand Down Expand Up @@ -755,9 +725,6 @@ static StructGVarFunc GVarFuncs [] = {
{ "InitRandomMT", 1, "initstr",
FuncInitRandomMT, "src/integer.c:InitRandomMT" },

{ "RandomListMT", 2, "mtstr, list",
FuncRandomListMT, "src/integer.c:RandomListMT" },

{ "INT_STRING", 1, "string",
FuncINT_STRING, "src/integer.c:INT_STRING" },

Expand Down
74 changes: 74 additions & 0 deletions tst/test32bit/randlist.tst
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@@ -0,0 +1,74 @@
#############################################################################
##
#W randlist.tst GAP library Frank Lübeck
##
##
#Y Copyright (C) 2016, The GAP Group
##
gap> START_TEST("randlist.tst");
gap> l := [1..2^(8*GAPInfo.BytesPerVariable-4)-1];
[ 1 .. 268435455 ]
gap> Reset(GlobalMersenneTwister, 1);;
gap> List([1..10], i-> Random(1, 2^70));
[ 389420078096435786116, 1135477438879460122740, 425191437180319830675,
1083900231106243887320, 600872374094649387692, 39438917363375403157,
860639563472417594821, 1064153947161477828981, 140455377727366448871,
198677943275448576238 ]
gap> List([1..10], i-> Random(l));
[ 13155435, 3131483, 21560873, 174688373, 142786538, 140745645, 25528157,
45625016, 214994737, 84644 ]
gap> List([1..10], i-> Random(1,10^(3*i)));
[ 721, 46797, 22238206, 187185663184, 734387696875236, 101821667962893342,
669052909362560486368, 769723171201061857635320,
874658974599856967310222061, 397063360144420204491778152435 ]
gap> Reset(GlobalRandomSource, 1);;
gap> List([1..10], i-> Random(GlobalRandomSource, 1, 2^70));
[ 1128431629504922105781, 1101744982711025966526, 975266616221323178376,
678285771456235093359, 337368903834409162500, 1067481644129172537859,
666712591436546208470, 471773889319658808870, 27293053954741592585,
894173925476383505759 ]
gap> List([1..10], i-> Random(GlobalRandomSource, l));
[ 40228334, 111587641, 262452744, 44854923, 39845682, 206581571, 92903376,
231314873, 66408590, 258714463 ]
gap> List([1..10], i-> Random(GlobalRandomSource, l)) mod 2^28;
[ 184978940, 159620597, 123129748, 68026743, 233471294, 232591449, 24005304,
5708683, 167299138, 197744113 ]
gap> List([1..10], i-> Random(GlobalRandomSource, 1,10^(3*i)));
[ 602, 615764, 985971579, 527993069062, 970982477709403, 915182928712255106,
52224684171237700022, 63091858766485771208964, 391269615753496331510430301,
929557928485066381724613674190 ]
gap> rs := RandomSource(IsMersenneTwister, 1);
<RandomSource in IsMersenneTwister>
gap> List([1..10], i-> Random(rs, 1, 2^70));
[ 389420078096435786116, 1135477438879460122740, 425191437180319830675,
1083900231106243887320, 600872374094649387692, 39438917363375403157,
860639563472417594821, 1064153947161477828981, 140455377727366448871,
198677943275448576238 ]
gap> List([1..10], i-> Random(rs, l));
[ 13155435, 3131483, 21560873, 174688373, 142786538, 140745645, 25528157,
45625016, 214994737, 84644 ]
gap> List([1..10], i-> Random(rs, 1,10^(3*i)));
[ 721, 46797, 22238206, 187185663184, 734387696875236, 101821667962893342,
669052909362560486368, 769723171201061857635320,
874658974599856967310222061, 397063360144420204491778152435 ]
gap> rs := RandomSource(IsGAPRandomSource, 1);
<RandomSource in IsGAPRandomSource>
gap> List([1..10], i-> Random(rs, 1, 2^70));
[ 1128431629504922105781, 1101744982711025966526, 975266616221323178376,
678285771456235093359, 337368903834409162500, 1067481644129172537859,
666712591436546208470, 471773889319658808870, 27293053954741592585,
894173925476383505759 ]
gap> List([1..10], i-> Random(rs, l));
[ 40228334, 111587641, 262452744, 44854923, 39845682, 206581571, 92903376,
231314873, 66408590, 258714463 ]
gap> List([1..10], i-> Random(rs, l)) mod 2^28;
[ 184978940, 159620597, 123129748, 68026743, 233471294, 232591449, 24005304,
5708683, 167299138, 197744113 ]
gap> List([1..10], i-> Random(rs, 1,10^(3*i)));
[ 602, 615764, 985971579, 527993069062, 970982477709403, 915182928712255106,
52224684171237700022, 63091858766485771208964, 391269615753496331510430301,
929557928485066381724613674190 ]
gap> STOP_TEST( "randlist.tst", 640000);
#############################################################################
##
#E
80 changes: 80 additions & 0 deletions tst/test64bit/randlist.tst
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@@ -0,0 +1,80 @@
#############################################################################
##
#W randlist.tst GAP library Frank Lübeck
##
##
#Y Copyright (C) 2016, The GAP Group
##
gap> START_TEST("randlist.tst");
gap> l := [1..2^(8*GAPInfo.BytesPerVariable-4)-1];
[ 1 .. 1152921504606846975 ]
gap> Reset(GlobalMersenneTwister, 1);;
gap> List([1..10], i-> Random(1, 2^70));
[ 389420078096435786116, 1135477438879460122740, 425191437180319830675,
1083900231106243887320, 600872374094649387692, 39438917363375403157,
860639563472417594821, 1064153947161477828981, 140455377727366448871,
198677943275448576238 ]
gap> List([1..10], i-> Random(l));
[ 13449613059603563, 750280845826784809, 604497940593164266,
195957948672214877, 363541010878257, 252402567376707281, 370012941179900926,
417909953390052908, 963123934602894316, 270776873282813509 ]
gap> List([1..10], i-> Random(1,10^(3*i)));
[ 200, 711160, 554290144, 155776019526, 905142534515704, 885417939216212735,
932340683886669498401, 455800814114634556722688,
791206551199537424739336406, 382559260149794825284857428764 ]
gap> Reset(GlobalRandomSource, 1);;
gap> List([1..10], i-> Random(GlobalRandomSource, 1, 2^70));
[ 1128431629504922105781, 1101744982711025966526, 975266616221323178376,
678285771456235093359, 337368903834409162500, 1067481644129172537859,
666712591436546208470, 471773889319658808870, 27293053954741592585,
894173925476383505759 ]
gap> List([1..10], i-> Random(GlobalRandomSource, l));
[ 172731053183754005, 399538608969287265, 528332786381188118,
719153818282315693, 341000865208262150, 994286057174428461,
975057260589483054, 343216463929586102, 60169085279927990,
236724101465774021 ]
gap> List([1..10], i-> Random(GlobalRandomSource, l)) mod 2^28;
[ 82408175, 222596625, 2843657, 140496253, 243545930, 128569490, 62441909,
102134268, 47094864, 154341103 ]
gap> List([1..10], i-> Random(GlobalRandomSource, 1,10^(3*i)));
[ 871, 264536, 392436441, 73737636655, 456525824458936, 890212987711716841,
234476903267325497175, 596997600529202583174722,
290628328961307271818818898, 17261260615457929009978390979 ]
gap> rs := RandomSource(IsMersenneTwister, 1);
<RandomSource in IsMersenneTwister>
gap> List([1..10], i-> Random(rs, 1, 2^70));
[ 389420078096435786116, 1135477438879460122740, 425191437180319830675,
1083900231106243887320, 600872374094649387692, 39438917363375403157,
860639563472417594821, 1064153947161477828981, 140455377727366448871,
198677943275448576238 ]
gap> List([1..10], i-> Random(rs, l));
[ 13449613059603563, 750280845826784809, 604497940593164266,
195957948672214877, 363541010878257, 252402567376707281, 370012941179900926,
417909953390052908, 963123934602894316, 270776873282813509 ]
gap> List([1..10], i-> Random(rs, 1,10^(3*i)));
[ 200, 711160, 554290144, 155776019526, 905142534515704, 885417939216212735,
932340683886669498401, 455800814114634556722688,
791206551199537424739336406, 382559260149794825284857428764 ]
gap> rs := RandomSource(IsGAPRandomSource, 1);
<RandomSource in IsGAPRandomSource>
gap> List([1..10], i-> Random(rs, 1, 2^70));
[ 1128431629504922105781, 1101744982711025966526, 975266616221323178376,
678285771456235093359, 337368903834409162500, 1067481644129172537859,
666712591436546208470, 471773889319658808870, 27293053954741592585,
894173925476383505759 ]
gap> List([1..10], i-> Random(rs, l));
[ 172731053183754005, 399538608969287265, 528332786381188118,
719153818282315693, 341000865208262150, 994286057174428461,
975057260589483054, 343216463929586102, 60169085279927990,
236724101465774021 ]
gap> List([1..10], i-> Random(rs, l)) mod 2^28;
[ 82408175, 222596625, 2843657, 140496253, 243545930, 128569490, 62441909,
102134268, 47094864, 154341103 ]
gap> List([1..10], i-> Random(rs, 1,10^(3*i)));
[ 871, 264536, 392436441, 73737636655, 456525824458936, 890212987711716841,
234476903267325497175, 596997600529202583174722,
290628328961307271818818898, 17261260615457929009978390979 ]
gap> STOP_TEST( "randlist.tst", 640000);
#############################################################################
##
#E
4 changes: 3 additions & 1 deletion tst/teststandard.g
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Expand Up @@ -37,7 +37,9 @@ Print( "You should start GAP4 using `gap -A -x 80 -r -m 100m -o 1g'.\n",

TestDirectory( [
Filename( DirectoriesLibrary( "tst" ), "teststandard" ),
Filename( DirectoriesLibrary( "tst" ), "testinstall" )],
Filename( DirectoriesLibrary( "tst" ), "testinstall" ),
Filename( DirectoriesLibrary( "tst" ),
Concatenation("test", String(8*GAPInfo.BytesPerVariable), "bit"))],
rec(exitGAP := true) );

# Should never get here
Expand Down