Random Number

Generate normally distributed random numbers

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Libraries:
Simulink / Sources

Description

The Random Number block generates normally distributed random numbers. To generate uniformly distributed random numbers, use the Uniform Random Number block. Both blocks use the Normal (Gaussian) random number generator ('v4': legacy MATLAB^® 4.0 generator of the rng function).

You can generate a repeatable sequence using any Random Number block with the same nonnegative seed and parameters. The seed resets to the specified value each time a simulation starts. By default, the block produces a sequence that has a mean of 0 and a variance of 1. To generate a vector of random numbers with the same mean and variance, specify the Seed parameter as a vector.

Avoid integrating a random signal, because solvers must integrate relatively smooth signals. Instead, use the Band-Limited White Noise block.

The numeric parameters of this block must have the same dimensions after scalar expansion. If you select the Interpret vector parameters as 1-D check box, and the numeric parameters are row or column vectors after scalar expansion, the block outputs a 1-D signal. If you clear the Interpret vector parameters as 1-D check box, the block outputs a signal of the same dimensionality as the parameters.

Examples

Variable-Size Signal Length Adaptation

Model showing how to change the length of a signal over time.

• Open Model

Ports

Output

Port_1 — Output signal

scalar | vector | matrix

Output signal that is the generated random numbers falling within a normal Gaussian distribution. The output is repeatable for a given seed.

Data Types: double

Parameters

Mean — Mean of random numbers

0 (default) | scalar | array

Specify the mean of the random numbers generated.

Programmatic Use

Block Parameter: Mean

Type: character vector

Values: scalar | array

Default: '0'

Variance — Variance of random numbers

1 (default) | scalar | array

Specify the variance of the random numbers.

Programmatic Use

Block Parameter: Variance

Type: character vector

Values: scalar | array

Default: '1'

Seed — Starting seed

0 (default) | positive integer | scalar | array

Specify the starting seed for the random number generator.

The output of number generated is repeatable for a given seed.

Programmatic Use

Block Parameter: Seed

Type: character vector

Values: scalar | array

Default: '0'

Sample time — Time between intervals

0.1 (default) | integer

Specify the time interval between samples. The default is 0.1, which matches the default sample time of the Band-Limited White Noise block. See Specify Sample Time for more information.

Programmatic Use

Block Parameter: SampleTime

Type: character vector

Values: scalar

Default: '0.1'

Interpret vector parameters as 1-D — Treat vectors as 1-D

on (default) | off

Select this check box to output a vector of length N if the Mean, Variance, and Seed parameters evaluate to an N-element row or column vector.

• When you select this check box, the block outputs a vector of length N if the Mean, Variance, and Seed parameters evaluate to an N-element row or column vector. For example, the block outputs a matrix of dimension 1-by-N or N-by-1.

• When you clear this check box, the block does not output a vector of length N if the Mean, Variance, and Seed parameters evaluate to an N-element row or column vector.

Programmatic Use

Block Parameter: VectorParams1D

Type: character vector

Values: 'on' | 'off'

Default: 'on'

Block Characteristics

Data Types	double
Direct Feedthrough	no
Multidimensional Signals	yes
Variable-Size Signals	no
Zero-Crossing Detection	no

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced before R2006a