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Subsections

RAND Uniform Random Number Generator

Usage

Creates an array of pseudo-random numbers of the specified size. The numbers are uniformly distributed on [0,1). Two seperate syntaxes are possible. The first syntax specifies the array dimensions as a sequence of scalar dimensions:

  y = rand(d1,d2,...,dn).

The resulting array has the given dimensions, and is filled with random numbers. The type of y is double, a 64-bit floating point array. To get arrays of other types, use the typecast functions.

The second syntax specifies the array dimensions as a vector, where each element in the vector specifies a dimension length:

  y = rand([d1,d2,...,dn]).

This syntax is more convenient for calling rand using a variable for the argument.

Example

The following example demonstrates an example of using the first form of the rand function.

--> rand(2,2,2)
ans = 
  <double>  - size: [2 2 2]
(:,:,1) = 
 
Columns 1 to 2
    0.814723686393179         0.126986816293506      
    0.905791937075619         0.913375856139019      
(:,:,2) = 
 
Columns 1 to 2
    0.632359246225410         0.278498218867048      
    0.0975404049994095        0.546881519204984

The second example demonstrates the second form of the rand function.

--> rand([2,2,2])
ans = 
  <double>  - size: [2 2 2]
(:,:,1) = 
 
Columns 1 to 2
    0.814723686393179         0.126986816293506      
    0.905791937075619         0.913375856139019      
(:,:,2) = 
 
Columns 1 to 2
    0.632359246225410         0.278498218867048      
    0.0975404049994095        0.546881519204984

The third example computes the mean and variance of a large number of uniform random numbers. Recall that the mean should be 1/2, and the variance should be 1/12 ~ 0.083.

--> x = rand(1,10000);
--> mean(x)
ans = 
  <double>  - size: [1 1]
    0.499560579911729      
--> var(x)
ans = 
  <double>  - size: [1 1]
    0.0829099953434714


next up previous contents
Next: Input/Ouput Functions Up: Random Number Generation Previous: RANDN Gaussian (Normal) Random   Contents
Samit K. Basu 2005-03-16