Posts Tagged ‘product’

Programming Praxis – Minimum Scalar Product

August 10, 2012

In today’s Programming Praxis exercise, our goal is to calculate the minimum scalar product of two vectors. Let’s get started, shall we?

A quick import:

import Data.List

Initially, I wrote a version that calculated all possible permutations and took the minimum value. After looking at the provided solution it turns out this isn’t necessary, which leads to the following shorter and more efficient version:

minScalar :: (Ord a, Num a) => [a] -> [a] -> a
minScalar a = sum . zipWith (*) (sort a) . reverse . sort

A test to see if everything is working properly:

main :: IO ()
main = print $ minScalar [1,3,-5] [-2,4,1] == -25