# gleam/float

Functions for working with floats.

## Division by zero

Gleam runs on the Erlang virtual machine, which does not follow the IEEE 754 standard for floating point arithmetic and does not have an `Infinity` value. In Erlang division by zero results in a crash, however Gleam does not have partial functions and operators in core so instead division by zero returns zero, a behaviour taken from Pony, Coq, and Lean.

This may seem unexpected at first, but it is no less mathematically valid than crashing or returning a special value. Division by zero is undefined in mathematics.

# Functions

## absolute_value

</>
``pub fn absolute_value(x: Float) -> Float``

Returns the absolute value of the input as a `Float`.

## Examples

``````> absolute_value(-12.5)
12.5
``````
``````> absolute_value(10.2)
10.2
``````

</>
``pub fn add(a: Float, b: Float) -> Float``

It’s the function equivalent of the `+.` operator. This function is useful in higher order functions or pipes.

## Examples

``````> add(1.0, 2.0)
3.0
``````
``````> import gleam/list
> list.fold([1.0, 2.0, 3.0], 0.0, add)
6.0
``````
``````> 3.0 |> add(2.0)
5.0
``````

## ceiling

</>
``pub fn ceiling(x: Float) -> Float``

Rounds the value to the next highest whole number as a `Float`.

## Examples

``````> ceiling(2.3)
3.0
``````

## clamp

</>
``````pub fn clamp(
x: Float,
min min_bound: Float,
max max_bound: Float,
) -> Float``````

Restricts a `Float` between a lower and upper bound.

## Examples

``````> clamp(1.2, min: 1.4, max: 1.6)
1.4
``````

## compare

</>
``pub fn compare(a: Float, with b: Float) -> Order``

Compares two `Float`s, returning an `Order`: `Lt` for lower than, `Eq` for equals, or `Gt` for greater than.

## Examples

``````> compare(2.0, 2.3)
Lt
``````

To handle Floating Point Imprecision you may use `loosely_compare` instead.

## divide

</>
``pub fn divide(a: Float, by b: Float) -> Result(Float, Nil)``

Returns division of the inputs as a `Result`.

## Examples

``````> divide(0.0, 1.0)
Ok(1.0)
``````
``````> divide(1.0, 0.0)
Error(Nil)
``````

## floor

</>
``pub fn floor(x: Float) -> Float``

Rounds the value to the next lowest whole number as a `Float`.

## Examples

``````> floor(2.3)
2.0
``````

## loosely_compare

</>
``````pub fn loosely_compare(
a: Float,
with b: Float,
tolerating tolerance: Float,
) -> Order``````

Compares two `Float`s within a tolerance, returning an `Order`: `Lt` for lower than, `Eq` for equals, or `Gt` for greater than.

This function allows Float comparison while handling Floating Point Imprecision.

Notice: For `Float`s the tolerance won’t be exact: `5.3 - 5.0` is not exactly `0.3`.

## Examples

``````> loosely_compare(5.0, with: 5.3, tolerating: 0.5)
Eq
``````

If you want to check only for equality you may use `loosely_equals` instead.

## loosely_equals

</>
``````pub fn loosely_equals(
a: Float,
with b: Float,
tolerating tolerance: Float,
) -> Bool``````

Checks for equality of two `Float`s within a tolerance, returning an `Bool`.

This function allows Float comparison while handling Floating Point Imprecision.

Notice: For `Float`s the tolerance won’t be exact: `5.3 - 5.0` is not exactly `0.3`.

## Examples

``````> loosely_equals(5.0, with: 5.3, tolerating: 0.5)
True
``````
``````> loosely_equals(5.0, with: 5.1, tolerating: 0.1)
False
``````

## max

</>
``pub fn max(a: Float, b: Float) -> Float``

Compares two `Float`s, returning the larger of the two.

## Examples

``````> max(2.0, 2.3)
2.3
``````

## min

</>
``pub fn min(a: Float, b: Float) -> Float``

Compares two `Float`s, returning the smaller of the two.

## Examples

``````> min(2.0, 2.3)
2.0
``````

## multiply

</>
``pub fn multiply(a: Float, b: Float) -> Float``

Multiplies two floats together.

It’s the function equivalent of the `*.` operator. This function is useful in higher order functions or pipes.

## Examples

``````> multiply(2.0, 4.0)
8.0
``````
``````import gleam/list
> list.fold([2.0, 3.0, 4.0], 1.0, multiply)
24.0
``````
``````> 3.0 |> multiply(2.0)
6.0
``````

## negate

</>
``pub fn negate(x: Float) -> Float``

Returns the negative of the value provided.

## Examples

``````> negate(1.0)
-1.0
``````

## parse

</>
``pub fn parse(string: String) -> Result(Float, Nil)``

Attempts to parse a string as a `Float`, returning `Error(Nil)` if it was not possible.

## Examples

``````> parse("2.3")
Ok(2.3)
``````
``````> parse("ABC")
Error(Nil)
``````

## power

</>
``````pub fn power(
base: Float,
of exponent: Float,
) -> Result(Float, Nil)``````

Returns the results of the base being raised to the power of the exponent, as a `Float`.

## Examples

``````> power(2.0, -1.0)
Ok(0.5)
``````
``````> power(2.0, 2.0)
Ok(4.0)
``````
``````> power(8.0, 1.5)
Ok(22.627416997969522)
``````
``````> 4.0 |> power(of: 2.0)
Ok(16.0)
``````
``````> power(-1.0, 0.5)
Error(Nil)
``````

## product

</>
``pub fn product(numbers: List(Float)) -> Float``

Multiplies a list of `Float`s and returns the product.

## Example

``````> product([2.5, 3.2, 4.2])
33.6
``````

## random

</>
``pub fn random(min: Float, max: Float) -> Float``

Generates a random float between the given minimum and maximum values.

## Examples

``````> random(1.0, 5.0)
2.646355926896028
``````

## round

</>
``pub fn round(x: Float) -> Int``

Rounds the value to the nearest whole number as an `Int`.

## Examples

``````> round(2.3)
2
``````
``````> round(2.5)
3
``````

## square_root

</>
``pub fn square_root(x: Float) -> Result(Float, Nil)``

Returns the square root of the input as a `Float`.

## Examples

``````> square_root(4.0)
Ok(2.0)
``````
``````> square_root(-16.0)
Error(Nil)
``````

## subtract

</>
``pub fn subtract(a: Float, b: Float) -> Float``

Subtracts one float from another.

It’s the function equivalent of the `-.` operator. This function is useful in higher order functions or pipes.

## Examples

``````> subtract(3.0, 1.0)
2.0
``````
``````> import gleam/list
> list.fold([1.0, 2.0, 3.0], 10.0, subtract)
4.0
``````
``````> 3.0 |> subtract(_, 2.0)
1.0
``````
``````> 3.0 |> subtract(2.0, _)
-1.0
``````

## sum

</>
``pub fn sum(numbers: List(Float)) -> Float``

Sums a list of `Float`s.

## Example

``````> sum([1.0, 2.2, 3.3])
6.5
``````

## to_string

</>
``pub fn to_string(x: Float) -> String``

Returns the string representation of the provided `Float`.

## Examples

``````> to_string(2.3)
"2.3"
``````

## truncate

</>
``pub fn truncate(x: Float) -> Int``

Returns the value as an `Int`, truncating all decimal digits.

## Examples

``````> truncate(2.4343434847383438)
2
``````