Lab1

fact n = product [1..n]

gcd' a 0 = a
gcd' a b = gcd' b (a `mod` b)

sqr x = x*x

isPrime 2 = True
isPrime x = x > 0 && odd x && primeIter x 3
    where primeIter x y = if sqr y > x
                            then True
                            else x `mod` y /= 0 && primeIter x (y+2)

revInt x = iter x 0
     where iter 0 res = res
           iter x acc = iter (x `div` 10) (acc * 10 + x `mod` 10)

solveSqr a b c =  if d<0
                  then []
                  else if d == 0
                  then [(-b)/(2*a)]
                  else [((-b)-(sqrt d))/(2*a),((-b)+(sqrt d))/(2*a)]
                  where d = b*b - 4*a*c


maxSolution a b c = case solution of
                    [] -> error "D<0!"
                    otherwise -> maximum solution
                    where solution = solveSqr a b c

root::(Double -> Double) -> Double -> Double -> Double -> Double
root f a b eps = if b - a < eps
                 then m
                 else if f m  == 0 then m
                 else if f a * f m > 0
                 then root f m b eps
                 else root f a m eps
                 where m = (b + a)/2