Copyright | Copyright (c) 2009-2013, David Sorokin <david.sorokin@gmail.com> |
---|---|

License | BSD3 |

Maintainer | David Sorokin <david.sorokin@gmail.com> |

Stability | experimental |

Safe Haskell | Safe-Inferred |

Language | Haskell98 |

Tested with: GHC 7.6.3

This module defines an unboxed variable that is bound up with the event queue and that keeps the history of changes storing the values in an unboxed array, which allows using the variable in differential and difference equations under some conditions.

- data Var a
- varChanged :: Var a -> Signal a
- varChanged_ :: Var a -> Signal ()
- newVar :: Unboxed a => a -> Simulation (Var a)
- readVar :: Unboxed a => Var a -> Event a
- writeVar :: Unboxed a => Var a -> a -> Event ()
- modifyVar :: Unboxed a => Var a -> (a -> a) -> Event ()
- freezeVar :: Unboxed a => Var a -> Event (Array Int Double, Array Int a)

# Documentation

Like the `Ref`

reference but keeps the history of changes in
different time points. The `Var`

variable is usually safe in the hybrid
simulation, for example, when it can be used in the differential or
difference equations unless you update the variable twice in the
same integration time point. Only this variable is much slower than
the reference.

varChanged :: Var a -> Signal a Source

Return a signal that notifies about every change of the variable state.

varChanged_ :: Var a -> Signal () Source

Return a signal that notifies about every change of the variable state.

newVar :: Unboxed a => a -> Simulation (Var a) Source

Create a new variable.

readVar :: Unboxed a => Var a -> Event a Source

Read the value of a variable.

It is safe to run the resulting computation with help of the `runEventWith`

function using modes `CurrentEventsOrFromPast`

and `EarlierEventsOrFromPast`

,
which is necessary if you are going to use the variable in the differential
or difference equations. Only it is preferrable if the variable is not updated twice
in the same integration time point; otherwise, different values can be returned
for the same point.

freezeVar :: Unboxed a => Var a -> Event (Array Int Double, Array Int a) Source

Freeze the variable and return in arrays the time points and corresponded values when the variable had changed in different time points: (1) the last actual value per each time point is provided and (2) the time points are sorted in ascending order.

If you need to get all changes including those ones that correspond to the same
simulation time points then you can use the `newSignalHistory`

function passing
in the `varChanged`

signal to it and then call function `readSignalHistory`

.