dotProduct :: Vector -> Vector -> Double
dotProduct (a1, a2, a3, a4) (b1, b2, b3, b4) =
   (a1 * b1 + a2 * b2 + a3 * b3 + a4 * b4)
dotProduct :: Vector -> Vector -> Double
dotProduct (a1, a2, a3, a4) (b1, b2, b3, b4) =
   (a1 * b1 + a2 * b2 + a3 * b3 + a4 * b4)
dotProduct (a1, a2, a3, a4) (b1, b2, b3, b4) =
   (a1 * b1 + a2 * b2 + a3 * b3 + a4 * b4)