The CQL commands `N`

, `LnN`

, `T`

, `U`

and `Top_Hat`

describe various types
of probability distribution functions. `cql_n()`

defines a normal distribution
by its mean and standard deviation; `cql_lnn()`

a log–normal distribution by
its mean and standard deviation; `cql_t()`

a Student's t distribution by
degrees of freedom; `cql_u()`

a uniform distribution by its start and end;
`cql_top_hat()`

a uniform distribution by its central point and width.

## Usage

```
cql_n(name, mu, sigma, resolution = NULL)
cql_lnn(name, mu, sigma, resolution = NULL)
cql_t(name, freedom, scale = 1, resolution = NULL)
cql_top_hat(name, mid, half_width)
cql_u(name, from, to, resolution = NULL)
```

## Arguments

- name
Character. Label for the distribution.

- mu
Integer. Mean of a normal or log–normal distribution.

- sigma
Integer. Standard deviation of a normal or log–normal distribution.

- resolution
Integer. Resolution of the PDF. Leave

`NULL`

(the default) to use the OxCal default.- freedom
Integer. Degrees of freedom of a Student's t distribution.

- scale
Numeric. Optional scaling parameter for a Student's t distribution.

- mid
Integer. Centre point of a uniform distribution.

- half_width
Integer. Half-width of a uniform distribution.

- from
Integer. Start point of a uniform distribution.

- to
Integer. End point of a uniform distribution.

## See also

Other CQL functions:
`cql_boundary()`

,
`cql_options()`

,
`cql_other`

,
`cql_phase()`

,
`cql_r_date()`

,
`cql_sequence()`

,
`cql()`

,
`write_oxcal()`

## Examples

```
# Describe a date as a uniform distribution
cql_date("U-Date", cql_u("U", -5000, -4000))
#> // CQL2 generated by stratigraphr v0.3.0.9000
#> Date("U-Date", U("U", -5000, -4000););
```