# FSim

An attempt at a simplest possible functional programming syntax for simulation model specification using the Fay embedded domain specific language (EDSL) and Javascript compiler.

The following code snippets are under test and might provide a basis for a first FSim.hs. They have mostly been lifted directly from other people’s code in Haskell or ported from other languages.

- Matrix operations
- Fourier transform (inverse missing)
- Euler’s method
- RK4
- Crank-Nicholson method
- Kalman filter
- Circuits
- Onsager
- misc.

## Models

- Ring oscillator
- Zero-dimension energy balance model (EBM)
- One-dimensional EBM
- Kamp advective ocean model
- Game of Life
- misc.

### Ring oscillator

Ian Ross’s “Fun with Fay” is a literate blog post using Fay and html5 canvas and a timer to display an animated 5 ring oscillator with dynamic graphs.

This seemed like a good example to start with but is too complicated for describing simple simulations.

The stripped-out user interfaceses html5 Options for parameter values. This avoids the FF non-working html5 slider problem.

Work is in progress on the simulation function (loop step? iterate step?) and graph rendering etc.

He also has another blog post on creating a good-looking jquery slider. Unfortunately this is for the Yesod web framework and needs to be ported to Snap TBD.

### Zero-Dimension EBM

I have no idea where these parameters came from, it’s merely for illustrative purposes.

#### In the Fay proper subset of Haskell

`testCO2 = temp 4.3`

`temp f = (-f)/totalF where`

` lambda0 = 3.2 :: Double -- Plank`

` totalF = avLambda - lambda0`

` avLambda = (maxSumF - minSumF)/2`

` minSumF = foldl (+) 0 (fmap fst lambda)`

` maxSumF = foldl (+) 0 (fmap snd lambda)`

` lambda = [waterVapour,lapseRate,clouds,albedo]`

` waterVapour = (1.48,2.14)`

` lapseRate = (-0.41,-1.27)`

` clouds = (0.18,1.18)`

` albedo = (0.07,0.34)`

This is supposed to be literate code so you should be able to cut and paste it into a text editor, save it as

<filename>.js and run it with node.js, ie.</filename>

` node <filename>.js

and get an answer of ~1.6 deg. C.

#### Dependency

node.js