Visual Servoing Platform  version 3.4.0
vpGaussRand Class Reference

`#include <vpGaussRand.h>`

## Public Member Functions

vpGaussRand ()

vpGaussRand (double sigma_val, double mean_val, long noise_seed=0)

void setSigmaMean (double sigma_val, double mean_val)

void seed (long seed_val)

double operator() ()

## Detailed Description

Class for generating random number with normal probability density.

The algorithms and notations used are described in [15].

The code below shows how to use the random generator to get values that have their mean equal to 10 with a standart deviation equal to 0.5.

#include <iostream>
#include <visp3/core/vpGaussRand.h>
int main()
{
vpGaussRand noise(0.5, 10);
for(int i=0; i< 10; i++) {
std::cout << "noise " << i << ": " << noise() << std::endl;
}
return 0;
}

The previous example produces the following printings:

noise 0: 10.645
noise 1: 9.67129
noise 2: 10.1208
noise 3: 10.1039
noise 4: 10.8667
noise 5: 9.89823
noise 6: 9.81414
noise 7: 9.96076
noise 8: 11.0795
noise 9: 9.79229

Note that the previous example produces always the same "random" results. To produce real random values, you need to initialize the random generator with different values using seed(). For example, this could be done using the current time. The code becomes:

#include <iostream>
#include <visp3/core/vpGaussRand.h>
#include <visp3/core/vpTime.h>
int main()
{
vpGaussRand noise(0.5, 10);
long seed = (long)vpTime::measureTimeMs();
noise.seed(seed);
for(int i=0; i< 10; i++) {
std::cout << "noise " << i << ": " << noise() << std::endl;
}
return 0;
}

Now if you run the previous example you will always get different values:

noise 0: 10.5982
noise 1: 9.19111
noise 2: 9.82498
noise 3: 9.07857
noise 4: 9.9285
noise 5: 10.3688
noise 6: 9.75621
noise 7: 10.3259
noise 8: 10.4238
noise 9: 10.2391
Examples:
testLineFitting.cpp, and testTukeyEstimator.cpp.

Definition at line 120 of file vpGaussRand.h.

## Constructor & Destructor Documentation

 vpGaussRand::vpGaussRand ( )
inline

Default noise generator constructor.

Definition at line 135 of file vpGaussRand.h.

 vpGaussRand::vpGaussRand ( double sigma_val, double mean_val, long noise_seed = `0` )
inline

Gaussian noise random generator constructor.

Parameters
 sigma_val : Standard deviation. mean_val : Mean value. noise_seed : Seed of the noise

Definition at line 144 of file vpGaussRand.h.

## Member Function Documentation

 double vpGaussRand::operator() ( )
inline

Return a random value from the Gaussian noise generator.

Definition at line 171 of file vpGaussRand.h.

 void vpGaussRand::seed ( long seed_val )
inline

Set the seed of the noise.

Parameters
 seed_val : New seed.
Examples:
testTukeyEstimator.cpp.

Definition at line 166 of file vpGaussRand.h.

References vpUniRand::setSeed().

 void vpGaussRand::setSigmaMean ( double sigma_val, double mean_val )
inline

Set the standard deviation and mean for gaussian noise.

Parameters
 sigma_val : New standard deviation sigma. mean_val : New mean value.

Definition at line 155 of file vpGaussRand.h.