gleam_community_maths - v1.1.0

gleam_community/maths/predicates

Predicates: A module containing functions for testing various mathematical properties of numbers.

Functions

all_close

</> 
pub fn all_close(
  xarr: List(Float),
  yarr: List(Float),
  rtol: Float,
  atol: Float,
) -> Result(List(Bool), String)

Determine if a list of values are close to or equivalent to a another list of reference values.

Example: 
import gleeunit/should
import gleam/list
import gleam_community/maths/tests

pub fn example () {
  let val: Float = 99.
  let ref_val: Float = 100.
  let xarr: List(Float) = list.repeat(val, 42)
  let yarr: List(Float) = list.repeat(ref_val, 42)
  // We set 'atol' and 'rtol' such that the values are equivalent
  // if 'val' is within 1 percent of 'ref_val' +/- 0.1
  let rtol: Float = 0.01
  let atol: Float = 0.10
  tests.all_close(xarr, yarr, rtol, atol)
  |> fn(zarr: Result(List(Bool), String)) -> Result(Bool, Nil) {
    case zarr {
      Ok(arr) ->
        arr
        |> list.all(fn(a: Bool) -> Bool { a })
        |> Ok
      _ -> Nil |> Error
    }
  }
  |> should.equal(Ok(True))
}

is_close

</> 
pub fn is_close(
  a: Float,
  b: Float,
  rtol: Float,
  atol: Float,
) -> Bool

Determine if a given value $$a$$ is close to or equivalent to a reference value $$b$$ based on supplied relative $$r_{tol}$$ and absolute $$a_{tol}$$ tolerance values. The equivalance of the two given values are then determined based on the equation:

\[ |a - b| \leq (a_{tol} + r_{tol} \cdot |b|) \]

True is returned if statement holds, otherwise False is returned.

Example 
import gleeunit/should
import gleam_community/maths/tests

pub fn example () {
  let val: Float = 99.
  let ref_val: Float = 100.
  // We set 'atol' and 'rtol' such that the values are equivalent
  // if 'val' is within 1 percent of 'ref_val' +/- 0.1
  let rtol: Float = 0.01
  let atol: Float = 0.10
  floatx.is_close(val, ref_val, rtol, atol)
  |> should.be_true()
}

is_even

</> 
pub fn is_even(x: Int) -> Bool

A function that tests whether a given integer value $$x \in \mathbb{Z}$$ is even.

Example: 
import gleeunit/should
import gleam_community/maths/tests

pub fn example() {
  tests.is_even(-3)
  |> should.equal(False)

  tests.is_even(-4)
  |> should.equal(True)
}

is_fractional

</> 
pub fn is_fractional(x: Float) -> Bool

Determine if a given value is fractional.

True is returned if the given value is fractional, otherwise False is returned.

Example 
import gleeunit/should
import gleam_community/maths/tests

pub fn example () {
  tests.is_fractional(0.3333)
  |> should.equal(True)
  
  tests.is_fractional(1.0)
  |> should.equal(False)
}

is_odd

</> 
pub fn is_odd(x: Int) -> Bool

A function that tests whether a given integer value $$x \in \mathbb{Z}$$ is odd.

Example: 
import gleeunit/should
import gleam_community/maths/tests

pub fn example() {
  tests.is_odd(-3)
  |> should.equal(True)

  tests.is_odd(-4)
  |> should.equal(False)
}

is_perfect

</> 
pub fn is_perfect(n: Int) -> Bool

A function that tests whether a given integer value $$n \in \mathbb{Z}$$ is a perfect number. A number is perfect if it is equal to the sum of its proper positive divisors.

Details

For example:

  • $$6$$ is a perfect number since the divisors of 6 are $$1 + 2 + 3 = 6$$.
  • $$28$$ is a perfect number since the divisors of 28 are $$1 + 2 + 4 + 7 + 14 = 28$$
Example: 
import gleeunit/should
import gleam_community/maths/tests

pub fn example() {
  tests.is_perfect(6)
  |> should.equal(True)

  tests.is_perfect(28)
  |> should.equal(True)
}

is_power

</> 
pub fn is_power(x: Int, y: Int) -> Bool

A function that tests whether a given integer value $$x \in \mathbb{Z}$$ is a power of another integer value $$y \in \mathbb{Z}$$.

Example: 
import gleeunit/should
import gleam_community/maths/tests

pub fn example() {
  // Check if 4 is a power of 2 (it is)
  tests.is_power(4, 2)
  |> should.equal(True)

  // Check if 5 is a power of 2 (it is not)
  tests.is_power(5, 2)
  |> should.equal(False)
}
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