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Scilab Help >> Control Systems - CACSD > noisegen

# noisegen

noise generation

### Syntax

`b = noisegen(pas, Tmax, sig)`

### Arguments

pas

real scalar, the time increment

Tmax

real scalar, the final time of the interval of noise generation

sig

real scalar, the standard deviation of the noise

### Description

`noisegen()` generates a Scilab function `b = Noise(t)` where `Noise(t)` is a piecewise constant function (constant on `[k*pas, (k+1)*pas]`). The value on each constant interval are random values from i.i.d Gaussian variables of standard deviation `sig`. The function is constant for `t <= 0` and `t >= Tmax`.

 Note: Random number generator functions such as rand and grand are another alternative to generate noises from a wide variety of probability distribution (see example 2 below).

### Examples

Example #1: noisegen()

```noisegen(0.5, 30, 1.0);
x = -5:0.01:35;
y = feval(x, Noise);
plot(x, y);```

Example #2: rand()

```// Plot a zero mean gaussian white noise with the variance 1.
// To use a different variance, multiply rand() by the square root of the variance.
t = 0:.5:30;
sig = 1; // Standard deviation of the white gaussian noise
noise = sig*rand(t, "normal");
plot2d2(t, noise);```