Create random number streams
[s1,s2,...] = RandStream.create('gentype','NumStreams',n)
s = RandStream.create('gentype')
[ ... ] = RandStream.create('gentype', Name, Value,...)
[s1,s2,...] = RandStream.create('gentype','NumStreams',n) creates n random
number streams that use the uniform pseudorandom number generator
algorithm specified by gentype. The streams are
independent in a pseudorandom sense. The streams are not necessarily
independent from streams created at other times. RandStream.list returns
all possible values for gentype or see Choosing a Random Number Generator for details on generator algorithms.
Multiple streams are not supported by all generator types. Use
either the multiplicative lagged Fibonacci generator (mlfg6331_64)
or the combined multiple recursive generator (mrg32k3a)
to create multiple streams.
s = RandStream.create('gentype') creates
a single random stream. The RandStream constructor
is a more concise alternative when you need to create a single stream.
[ ... ] = RandStream.create('gentype', Name, Value,...) allows
you to specify optional Name, Value pairs to control creation of
the stream. The parameters are:
NumStreams | Total number of streams of this type that will be created across sessions or labs. Default is 1. |
StreamIndices | Stream indices that should be created in this call. Default
is 1:N, where N is the value
given with the 'NumStreams' parameter. |
Seed | Nonnegative scalar integer with which to initialize all streams.
Default is 0. Seeds must be an integer between 0 and 232 −
1 or 'shuffle' to create a seed based on the
current time. |
NormalTransform | Transformation algorithm used by randn(S, ...) to
generate normal pseudorandom values. Options are 'Ziggurat', 'Polar',
or 'Inversion'. |
CellOutput | Logical flag indicating whether or not to return the stream objects as elements of a cell array. Default is false. |
Typically, you call RandStream.create once
to create multiple independent streams in a single pass. Alternatively,
you can create each stream from separate calls to RandStream.create,
but you must specify the appropriate values for gentype, 'NumStreams', 'Seed',
and 'StreamIndices' to ensure their independence:
Specify the same set of values for gentype, 'NumStreams',
and 'Seed' in each case.
Specify a different value for 'StreamIndices' that
is between 1 and the 'NumStreams' value
in each case.
Create three independent streams.
[s1,s2,s3] = RandStream.create('mrg32k3a','NumStreams',3);
r1 = rand(s1,100000,1);
r2 = rand(s2,100000,1);
r3 = rand(s3,100000,1);
corrcoef([r1,r2,r3])Create one stream from a set of three independent streams and designate it as the global stream.
s2 = RandStream.create('mrg32k3a','NumStreams',3,'StreamIndices',2);
RandStream.setGlobalStream(s2);