Rand()

>> help Rand

 RAND Uniformly distributed pseudorandom numbers.

    R = RAND(N) returns an N-by-N matrix containing pseudorandom values drawn

    from the standard uniform distribution on the open interval(0,1).  RAND(M,N)

    or RAND([M,N]) returns an M-by-N matrix.  RAND(M,N,P,...) or

    RAND([M,N,P,...]) returns an M-by-N-by-P-by-... array.  RAND returns a

    scalar.  RAND(SIZE(A)) returns an array the same size as A.

 

    Note: The size inputs M, N, P, ... should be nonnegative integers.

    Negative integers are treated as 0.

 

    R = RAND(..., 'double') or R = RAND(..., 'single') returns an array of

    uniform values of the specified class.

 

    Compatibility Note: In versions of MATLAB prior to 7.7, you controlled

    the internal state of the random number stream used by RAND by calling

    RAND directly with the 'seed', 'state', or 'twister' keywords.  That

    syntax is still supported for backwards compatibility, but is deprecated.

    Beginning in MATLAB 7.7, use the default stream as described in

    RANDSTREAM. ＊これは知らなかった。

 

    The sequence of numbers produced by RAND is determined by the internal

    state of the uniform pseudorandom number generator that underlies RAND,

    RANDI, and RANDN.  Control that default random number stream using its

    properties and methods.  See RANDSTREAM for details about the default

    stream.

 

    Resetting the default stream to the same fixed state allows computations

    to be repeated.  Setting the stream to different states leads to unique

    computations, however, it does not improve any statistical properties.

    Since MATLAB uses the same state each time it starts up, RAND, RANDN, and

    RANDI will generate the same sequence of numbers in each session unless

    the state is changed.

 

    Examples:

 

       Generate values from the uniform distribution on the interval [a, b].

          r = a + (b-a).*rand(100,1);

 

       Generate integer values from the uniform distribution on the set 1:n.

          r = randi(100,1);

 

       Save the current state of the default stream, generate 5 values,

       restore the state, and repeat the sequence.

          defaultStream = RandStream.getDefaultStream;

          savedState = defaultStream.State;

          u1 = rand(1,5)

          defaultStream.State = savedState;

          u2 = rand(1,5) % contains exactly the same values as u1

 

       Replace the default stream with a stream whose seed is based on CLOCK, so

       RAND will return different values in different MATLAB sessions.  NOTE: It

       is usually not desirable to do this more than once per MATLAB session.

          RandStream.setDefaultStream(RandStream('mt19937ar','seed',sum(100*clock)));

          rand(1,5)

 ＊これを使う。

    See also Randi, randn, RandStream, RandStream/rand, RandStream/getDefaultStream,

             sprand, sprandn, randperm.

    Overloaded methods:

       RandStream/rand

    Reference page in Help browser

       doc rand

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