simulateReturns :: Float -> Int -> Float -> Float -> Float -> IO [Float]
simulateReturns sigma kbar gamma_kbar b m0 = do
  volatility <- simulateVolatility sigma kbar gamma_kbar b m0
  gen <- newStdGen
  let rand = (randomRs (-1,1) gen) :: [Float]
  let ret = zipWith (*) rand volatility
  return ret
simulateReturns :: Float -> Int -> Float -> Float -> Float -> IO [Float]
simulateReturns sigma kbar gamma_kbar b m0 = do
  volatility <- simulateVolatility sigma kbar gamma_kbar b m0
  gen <- newStdGen
  let rand = (randomRs (-1,1) gen) :: [Float]
  let ret = zipWith (*) rand volatility
  return ret
simulateReturns sigma kbar gamma_kbar b m0 = do
  volatility <- simulateVolatility sigma kbar gamma_kbar b m0
  gen <- newStdGen
  let rand = (randomRs (-1,1) gen) :: [Float]
  let ret = zipWith (*) rand volatility
  return ret