https://github.com/comius/haskell-fast-reals

A fast implementation of real numbers in Haskell
https://github.com/comius/haskell-fast-reals

Last synced: 2 months ago
JSON representation

A fast implementation of real numbers in Haskell

• Host: GitHub
• URL: https://github.com/comius/haskell-fast-reals
• Owner: comius
• License: bsd-2-clause
• Created: 2015-07-27T17:52:50.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2019-03-25T16:34:03.000Z (almost 6 years ago)
• Last Synced: 2023-03-24T06:00:22.654Z (almost 2 years ago)
• Language: Haskell
• Size: 110 KB
• Stars: 9
• Watchers: 4
• Forks: 2
• Open Issues: 4
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
A library for computing with exact real numbers in Haskell.

## Prerequisites

* A generally working development environment (`make`, `gcc`)

* Probably the [GMP](https://gmplib.org) header files.

* Haskell version 7.8.4, including Cabal

* The [haskell-mpfr](https://github.com/comius/haskell-mpfr) library by [Ivo List](https://github.com/comius).

The MPFR Haskell bindings in the haskell-mpfr library rely on low-level implementation details

of Haskell. It is likely they will break with newer versions of Haskell.

## Installation & Usage

1. Install the haskell-mpfr library, following the instructions there. Essentially, it is just a `cabal install` inside the haskell-mpfr source directory.

2. To install the library, run

        cabal install

   To get a version of the library which allows profiling, use instead

        cabal install --ghc-option=-fprof-auto -p --enable-executable-profiling

3. Alternatively to the previous step, you can run

        cabal repl

   to get an interactive shell with the library preloaded. This way you can try out the

   library without installing it.

4. To create HTML documentation run

        cabal haddock

   The generated HTML files will be placed in `dist/doc/html/`.

## Example

Here is an example session.

    Preprocessing library haskell-fast-reals-0.1.0.0...

    GHCi, version 7.8.4: http://www.haskell.org/ghc/  :? for help

    <... stuff gets loaded ...>

    *Data.Reals.Reals> let a = 1.3 :: RealNum

    *Data.Reals.Reals> a*(1-a)

    [-3.900000000007822e-1,-3.899999999994179e-1]

    *Data.Reals.Reals> a / a

    [9.999999999972715e-1,1.000000000001819]

    *Data.Reals.Reals> let b = 2.7 :: RealNum

    *Data.Reals.Reals> a * a - b * b - (a + b) * (a - b)

    [-3.128661774106285e-12,4.147295840103611e-12]

    *Data.Reals.Reals> a * a

    [1.689999999996871,1.690000000004147]

    *Data.Reals.Reals> approx (a * a) (precUp 100)

    [1.69,1.69]

    λ> let int =  (ClosedInterval (appFromInteger 0,appFromInteger 1))

    λ> forall int $ \x -> (x * (1 - x)) `less` (0.24 :: RealNum )

    False

    λ> forall int $ \x -> (x * (1 - x)) `less` (0.26 :: RealNum )

    True