A brief gradient descent illustration in Haskell

Grad.hs

descent1D gradF iterN gamma x0 = take iterN (iterate _descend x0)
  where
    _descend gamma' x = x - gamma' * gradF x
    
-- Suppose, we have a function F(x) = (x - 3)^2.
-- Therefore, Grad F(x) = 2 * (x - 3).
gradF_test x = 2 * (x - 3)

main = print (descent1D gradF_test 10 gamma 0.0)
  where gamma = 0.5