26
Numerics library
[numerics]
26.6
Random number generation
[rand]
26.6.9
Random number distribution class templates
[rand.dist]
26.6.9.4
Poisson distributions
[rand.dist.pois]
26.6.9.4.2
Class template
exponential_distribution
[rand.dist.pois.exp]
1
#
An
exponential_distribution
random number distribution produces random numbers
x
>
0
distributed according to the probability density function
p
(
x
|
λ
)
=
λ
e
−
λ
x
.
🔗
template
<
class
RealType
=
double
>
class
exponential_distribution
{
public
:
// types
using
result_type
=
RealType;
using
param_type
=
unspecified
;
// constructors and reset functions
exponential_distribution
(
)
:
exponential_distribution
(
1.0
)
{
}
explicit
exponential_distribution
(
RealType lambda
)
;
explicit
exponential_distribution
(
const
param_type
&
parm
)
;
void
reset
(
)
;
// generating functions
template
<
class
URBG
>
result_type
operator
(
)
(
URBG
&
g
)
;
template
<
class
URBG
>
result_type
operator
(
)
(
URBG
&
g,
const
param_type
&
parm
)
;
// property functions
RealType lambda
(
)
const
; param_type param
(
)
const
;
void
param
(
const
param_type
&
parm
)
; result_type min
(
)
const
; result_type max
(
)
const
;
}
;
🔗
explicit
exponential_distribution
(
RealType lambda
)
;
2
#
Preconditions
:
0
<
lambda
.
3
#
Remarks
:
lambda
corresponds to the parameter of the distribution
.
🔗
RealType lambda
(
)
const
;
4
#
Returns
: The value of the
lambda
parameter with which the object was constructed
.