Get Denominator from a Rational Number in Haskell

In Haskell, we can use denominator, div, quot and gcd functions to obtain the denominator from a rational number. In the first example we are going to use (denominator r) function and in the second example, we are going to use (d `div` gcd n d) function.

Algorithm

• Step 1 ? The Data.Ratio module is imported to use denominator function.

• Step 2 ? Program execution will be started from main function. The main() function has whole control of the program. It is written as main = do. It calls the denominator function with the rational number and prints the denominator.

• Step 3 ? The variable named, "r" is being initialized. It will hold the rational number value whose denominator is to be printed.

• Step 4 ? The resultant denominator value is printed to the console using ?putStrLn' statement after the function is called.

Example 1

In this example, we are going to see that how we can get the denominator from the rational number by using denominator function.

import Data.Ratio

main :: IO ()
main = do
   let r = 3 % 4
   let num = denominator r
   putStrLn $ "The denominator of " ++ show r ++ " is: " ++ show num

Output

The denominator of 3 % 4 is: 4

Example 2

In this example, we are going to see that how we can get the denominator from the rational number by using div and gcd function.

import Data.Ratio

getdenominator :: Rational -> Integer
getdenominator r = d `div` gcd n d where
   n = numerator r
   d = denominator r

main :: IO ()
main = do
   let r = 3 % 4
   let num = getdenominator r
   putStrLn $ "The denominator of " ++ show r ++ " is: " ++ show num

Output

The denominator of 3 % 4 is: 4

Example 3

In this example, we are going to see that how we can get the denominator from the rational number by using quot and gcd function.

import Data.Ratio

getdenominator :: Rational -> Integer
getdenominator r = denominator r `quot` gcd (numerator r) (denominator r)

main :: IO ()
main = do
   let r = 3 % 4
   let num = getdenominator r
   putStrLn $ "The denominator of " ++ show r ++ " is: " ++ show num

Output

The denominator of 3 % 4 is: 4

Conclusion

The denominator of a rational number is the bottom part of the fraction. In other words, it is the number by which the numerator is divided with.