---
name: "random"
section: "3tcllib"
platform: "linux"
package: "tcllib"
version: "1.12-dfsg-2"
release: "Debian 6.0 (Squeeze)"
platforms: ["linux"]
url: "https://new.carta.tech/random/3tcllib"
---

# random(3tcllib)

Pseudo-random number generators

```

```

## NAME

simulation::random - Pseudo-random number generators

## SYNOPSIS

package require **Tcl  ?8.4?**

package require **simulation::random  0.1**

**::simulation::random::prng\_Bernoulli** *p*

**::simulation::random::prng\_Discrete** *n*

**::simulation::random::prng\_Poisson** *lambda*

**::simulation::random::prng\_Uniform** *min* *max*

**::simulation::random::prng\_Exponential** *min* *mean*

**::simulation::random::prng\_Normal** *mean* *stdev*

**::simulation::random::prng\_Pareto** *min* *steep*

**::simulation::random::prng\_Gumbel** *min* *f*

**::simulation::random::prng\_chiSquared** *df*

**::simulation::random::prng\_Disk** *rad*

**::simulation::random::prng\_Sphere** *rad*

**::simulation::random::prng\_Ball** *rad*

**::simulation::random::prng\_Rectangle** *length* *width*

**::simulation::random::prng\_Block** *length* *width* *depth*

```

```

## DESCRIPTION

This package consists of commands to generate pseudo-random number generators. These new commands deliver

- •

  numbers that are distributed normally, uniformly, according to a Pareto or Gumbel distribution and so on

- •

  coordinates of points uniformly spread inside a sphere or a rectangle

For example:

```
    set p [::simulation::random::prng_Normal -1.0 10.0]
```

produces a new command (whose name is stored in the variable "p") that generates normally distributed numbers with a mean of -1.0 and a standard deviation of 10.0.

## PROCEDURES

The package defines the following public procedures for *discrete* distributions:

- **::simulation::random::prng\_Bernoulli** *p*

  Create a command (PRNG) that generates numbers with a Bernoulli distribution: the value is either 1 or 0, with a chance p to be 1

  - float *p*

    Chance the outcome is 1

- **::simulation::random::prng\_Discrete** *n*

  Create a command (PRNG) that generates numbers 0 to n-1 with equal probability.

  - int *n*

    Number of different values (ranging from 0 to n-1)

- **::simulation::random::prng\_Poisson** *lambda*

  Create a command (PRNG) that generates numbers according to the Poisson distribution.

  - float *lambda*

    Mean number per time interval

The package defines the following public procedures for *continuous* distributions:

- **::simulation::random::prng\_Uniform** *min* *max*

  Create a command (PRNG) that generates uniformly distributed numbers between "min" and "max".

  - float *min*

    Minimum number that will be generated

  - float *max*

    Maximum number that will be generated

- **::simulation::random::prng\_Exponential** *min* *mean*

  Create a command (PRNG) that generates exponentially distributed numbers with a given minimum value and a given mean value.

  - float *min*

    Minimum number that will be generated

  - float *mean*

    Mean value for the numbers

- **::simulation::random::prng\_Normal** *mean* *stdev*

  Create a command (PRNG) that generates normally distributed numbers with a given mean value and a given standard deviation.

  - float *mean*

    Mean value for the numbers

  - float *stdev*

    Standard deviation

- **::simulation::random::prng\_Pareto** *min* *steep*

  Create a command (PRNG) that generates numbers distributed according to Pareto with a given minimum value and a given distribution steepness.

  - float *min*

    Minimum number that will be generated

  - float *steep*

    Steepness of the distribution

- **::simulation::random::prng\_Gumbel** *min* *f*

  Create a command (PRNG) that generates numbers distributed according to Gumbel with a given minimum value and a given scale factor. The probability density function is:

  ```
       P(v) = exp( -exp(f*(v-min)))
  ```

  - float *min*

    Minimum number that will be generated

  - float *f*

    Scale factor for the values

- **::simulation::random::prng\_chiSquared** *df*

  Create a command (PRNG) that generates numbers distributed according to the chi-squared distribution with df degrees of freedom. The mean is 0 and the standard deviation is 1.

  - float *df*

    Degrees of freedom

The package defines the following public procedures for random point sets:

- **::simulation::random::prng\_Disk** *rad*

  Create a command (PRNG) that generates (x,y)-coordinates for points uniformly spread over a disk of given radius.

  - float *rad*

    Radius of the disk

- **::simulation::random::prng\_Sphere** *rad*

  Create a command (PRNG) that generates (x,y,z)-coordinates for points uniformly spread over the surface of a sphere of given radius.

  - float *rad*

    Radius of the disk

- **::simulation::random::prng\_Ball** *rad*

  Create a command (PRNG) that generates (x,y,z)-coordinates for points uniformly spread within a ball of given radius.

  - float *rad*

    Radius of the ball

- **::simulation::random::prng\_Rectangle** *length* *width*

  Create a command (PRNG) that generates (x,y)-coordinates for points uniformly spread over a rectangle.

  - float *length*

    Length of the rectangle (x-direction)

  - float *width*

    Width of the rectangle (y-direction)

- **::simulation::random::prng\_Block** *length* *width* *depth*

  Create a command (PRNG) that generates (x,y)-coordinates for points uniformly spread over a block

  - float *length*

    Length of the block (x-direction)

  - float *width*

    Width of the block (y-direction)

  - float *depth*

    Depth of the block (z-direction)

## KEYWORDS

math, random numbers, simulation, statistical distribution

## CATEGORY

Mathematics

## COPYRIGHT

```
Copyright (c) 2004 Arjen Markus <arjenmarkus@users.sourceforge.net>
```