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numbers package provides instances of numerical classes for different types of numbers - (computable) real numbers, precison fixed numbers, floating point numbers, differentiable numbers, symbolic numbers, and interval arithmetic. It is now available in Fedora. Install it using:

`` \$ sudo yum install ghc-numbers-devel``

For interval arithmentic, Interval is defined as a type constructor:

``data Interval a = I a a``

The ival function two arguments of the same type and returns an Interval a, while, the getIval function takes an interval and returns a pair.

``````ghci> :m + Data.Number.Interval

ghci> ival 1 2
1..2

ghci> getIval (ival 3 4)
(3,4)``````

The CReal type implements (constructive) real numbers. The showCReal function takes a number of decimals, a real number, and returns a string.

``````ghci> :m + Data.Number.CReal

ghci> showCReal 5 pi
"3.14159"``````

The Dif type is a type defined for differentiable numbers. The dCon function takes a number and constructs a Dif number with the same value, while the val function does the opposite.

``````ghci> :m + Data.Number.Dif

ghci> dCon 3
3~~

ghci> val (dCon 5)
5``````

The mkDif function takes a value and a Dif value and makes a Dif number as its derivative.

``````ghci> mkDif 4 (dCon 2)
4~~``````

The deriv function takes a derivative of a function. For example, if we have an equation f(x)=x2, then the first derivative, f’(x)=2x. This can be defined as:

``````ghci> let f x = x * x
ghci> let f' = deriv f

ghci> f 3
9

ghci> f' 3
6``````