---
name: "std::tr1::geometric_distribution"
section: "3"
platform: "linux"
package: "libstdc++6-4.2-doc"
version: "4.2.4-6"
release: "Debian 5.0 (Lenny)"
platforms: ["linux"]
url: "https://new.carta.tech/std::tr1::geometric_distribution"
---

# std::tr1::geometric\_distribution(3)

## NAME

std::tr1::geometric\_distribution -

## SYNOPSIS

## Detailed Description

### template\<typename \_IntType = int, typename \_RealType = double\> class std::tr1::geometric\_distribution\< \_IntType, \_RealType \>

The formula for the geometric probability mass function is $ p(i) = (1 - p)p^{i-1} $ where $ p $ is the parameter of the distribution.

Definition at line 1743 of file random.

### Public Types

typedef \_RealType **input\_type**\
 typedef \_IntType **result\_type**\

### Public Member Functions

**geometric\_distribution** (const \_RealType &\_\_p=\_RealType(0.5))\
 template\<class \_UniformRandomNumberGenerator\> result\_type **operator()** (\_UniformRandomNumberGenerator &\_\_urng)\
 \_RealType **p** () const \
 void **reset** ()\

### Friends

template\<typename \_IntType1, typename \_RealType1, typename \_CharT, typename \_Traits\> **std::basic\_ostream**\< \_CharT, \_Traits \> & **operator\<\<** (**std::basic\_ostream**\< \_CharT, \_Traits \> &\_\_os, const **geometric\_distribution**\< \_IntType1, \_RealType1 \> &\_\_x)\
 template\<typename \_CharT, typename \_Traits\> **std::basic\_istream**\< \_CharT, \_Traits \> & **operator\>\>** (**std::basic\_istream**\< \_CharT, \_Traits \> &\_\_is, **geometric\_distribution** &\_\_x)\

## Member Function Documentation

### template\<typename \_IntType = int, typename \_RealType = double\> \_RealType std::tr1::geometric\_distribution\< \_IntType, \_RealType \>::p () const` [inline]`

Gets the distribution parameter `p`.

Definition at line 1763 of file random.

## Friends And Related Function Documentation

### template\<typename \_IntType = int, typename \_RealType = double\> template\<typename \_IntType1, typename \_RealType1, typename \_CharT, typename \_Traits\> std::basic\_ostream\<\_CharT, \_Traits\>& operator\<\< (std::basic\_ostream\< \_CharT, \_Traits \> & \_\_os, const geometric\_distribution\< \_IntType1, \_RealType1 \> & \_\_x)` [friend]`

Inserts a geometric\_distribution random number distribution `__x` into the output stream `__os`.

**Parameters:**

*\_\_os* An output stream. \
 *\_\_x* A geometric\_distribution random number distribution.

**Returns:**

The output stream with the state of `__x` inserted or in an error state.

### template\<typename \_IntType = int, typename \_RealType = double\> template\<typename \_CharT, typename \_Traits\> std::basic\_istream\<\_CharT, \_Traits\>& operator\>\> (std::basic\_istream\< \_CharT, \_Traits \> & \_\_is, geometric\_distribution\< \_IntType, \_RealType \> & \_\_x)` [friend]`

Extracts a geometric\_distribution random number distribution `__x` from the input stream `__is`.

**Parameters:**

*\_\_is* An input stream. \
 *\_\_x* A geometric\_distribution random number generator engine.

**Returns:**

The input stream with `__x` extracted or in an error state.

Definition at line 1800 of file random.

## Author

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