Dear Forum,
Bruce Colletti wrote:
In GAP 4.4.9, I want to create a random matrix of arbitrarily large integers.
> However, I must be able to reset the random number stream so that the same
matrices
> can be regenerated.
How is this done using RandomMat?
There are two things:
- Random sources can be initialized by the operation `Reset'.
For the documentation of random sources, see ?Random sources.
E.g.:
gap> Reset(GlobalMersenneTwister);;
gap> RandomMat(2,3,Integers);
[ [ -1, -4, -1 ], [ -3, -2, 1 ] ]
gap> Reset(GlobalMersenneTwister);;
gap> RandomMat(2,3,Integers);
[ [ -1, -4, -1 ], [ -3, -2, 1 ] ]
- `RandomMat' does not produce matrices with arbitrarily large entries.
However you can just write your own little function, e.g.:
RandomLargeIntegerMat := function ( n, m, bound )
return List([1..n],i->List([1..m],j->Random(-bound,bound)));
end;
Then the rest is straightforward:
gap> Reset(GlobalMersenneTwister);;
gap> RandomLargeIntegerMat(2,3,10^20);
[ [ 35478973841434169085, -5727827082917039741, 30043532000967004818 ],
[ 98456515568185409751, -23365773455484833982, 29964620678188938398 ] ]
gap> Reset(GlobalMersenneTwister);;
gap> RandomLargeIntegerMat(2,3,10^20);
[ [ 35478973841434169085, -5727827082917039741, 30043532000967004818 ],
[ 98456515568185409751, -23365773455484833982, 29964620678188938398 ] ]
Hope this helps,
Stefan Kohl
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