{-# LANGUAGE RecursiveDo #-} -- Example: Simulation of a Bouncing Ball. -- -- It is described in MATLAB & Simulink example available by the following link: -- -- http://www.mathworks.com/help/simulink/examples/simulation-of-a-bouncing-ball.html import Control.Monad import Control.Monad.Trans import Simulation.Aivika.Trans import Simulation.Aivika.Trans.SystemDynamics import Simulation.Aivika.IO type SD = IO -- | The simulation specs. specs = Specs { spcStartTime = 0.0, spcStopTime = 25.0, spcDT = 0.01, spcMethod = RungeKutta4, spcGeneratorType = SimpleGenerator } -- the acceleration due to gravity g = 9.81 -- the initial velocity v0 = 15 -- the initial position x0 = 10 -- the coefficient of restitution of the ball k = 0.8 model :: Simulation SD (Results SD) model = mdo v <- integEither dv v0 x <- integEither dx x0 let dv = do x' <- x v' <- v if x' < 0 then return \$ Left (- k * v') else return \$ Right (- g) dx = do x' <- x v' <- v if x' < 0 then return \$ Left 0 else return \$ Right v' return \$ results [resultSource "t" "time" time, resultSource "x" "position" x, resultSource "v" "velocity" v] main = printSimulationResultsInStopTime printResultSourceInEnglish model specs