Scilab Home page | Wiki | Bug tracker | Forge | Mailing list archives | ATOMS | File exchange
Scilab-Branch-6.1-GIT
Change language to: Français - Português - 日本語 - Русский
Scilab Help >> Elementary Functions > Matrix generation > random > noisegen

noisegen

noise generation (obsolete)

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 `noisegen()` is obsolete. It will be removed from Scilab 6.1.x. Please use grand() instead. Examples (clearer, shorter, and more powerful) follow: 100 10-point wide steps with random amplitudes of normal distribution of mean 1 and standard deviation 0.7: ```u = grand(1,100,"nor",1,0.7) .*. ones(1,10); clf, plot(u);``` 40 15-point wide steps with random amplitudes of uniform distribution in [1 3], with initial level 0.5 and final level hold: ```width = 15; u = grand(1,40, "unf", 1, 3) .*. ones(1,width); u = [ones(1,8*width)*0.5, u, ones(1,5*width)*u(\$)]; clf, plot(u);```

`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);```

• rand — Random numbers
• grand — Random numbers

History

 Version Description 6.1.0 noisegen() is obsolete. It will be removed from Scilab 6.1.x. Please replace it with grand() and .*.