From b281a09e3fa5ffbdfcd621e810058fb5c9350a19 Mon Sep 17 00:00:00 2001
From: Dominic Steinitz <dominic@steinitz.org>
Date: Sat, 21 Apr 2018 16:14:46 +0100
Subject: Build examples via stack (start of)

---
 examples/sundials.hs | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 examples/sundials.hs

(limited to 'examples')

diff --git a/examples/sundials.hs b/examples/sundials.hs
new file mode 100644
index 0000000..1643540
--- /dev/null
+++ b/examples/sundials.hs
@@ -0,0 +1,48 @@
+{-# LANGUAGE ViewPatterns #-}
+import           Numeric.Sundials.ARKode.ODE
+import           Numeric.LinearAlgebra
+import           Graphics.Plot
+
+vanderpol mu = do
+    let xdot mu t [x,v] = [v, -x + mu * v * (1-x^2)]
+        ts = linspace 1000 (0,50)
+        sol = toColumns $ odeSolve (xdot mu) [1,0] ts
+    mplot (ts : sol)
+    mplot sol
+
+
+harmonic w d = do
+    let xdot w d t [x,v] = [v, a*x + b*v] where a = -w^2; b = -2*d*w
+        ts = linspace 100 (0,20)
+        sol = odeSolve (xdot w d) [1,0] ts
+    mplot (ts : toColumns sol)
+
+
+kepler v a = mplot (take 2 $ toColumns sol) where
+    xdot t [x,y,vx,vy] = [vx,vy,x*k,y*k]
+        where g=1
+              k=(-g)*(x*x+y*y)**(-1.5)
+    ts = linspace 100 (0,30)
+    sol = odeSolve xdot [4, 0, v * cos (a*degree), v * sin (a*degree)] ts
+    degree = pi/180
+
+
+main = do
+    vanderpol 2
+    harmonic 1 0
+    harmonic 1 0.1
+    kepler 0.3 60
+    kepler 0.4 70
+    vanderpol' 2
+
+-- example of odeSolveV with jacobian
+vanderpol' mu = do
+    let xdot mu t (toList->[x,v]) = fromList [v, -x + mu * v * (1-x^2)]
+        jac t (toList->[x,v]) = (2><2) [ 0          ,          1
+                                       , -1-2*x*v*mu, mu*(1-x**2) ]
+        ts = linspace 1000 (0,50)
+        hi = pure $ (ts!1 - ts!0) / 100.0
+        sol = toColumns $ odeSolveV (SDIRK_5_3_4 jac) hi 1E-8 1E-8 (xdot mu) (fromList [1,0]) ts
+    mplot sol
+
+
-- 
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