add examples

1 files changed, 17 insertions, 0 deletions

diff --git a/examples/integrate.hs b/examples/integrate.hs
new file mode 100644
index 0000000..6da88ad
--- /dev/null
+++ b/examples/integrate.hs
@@ -0,0 +1,17 @@
+-- Numerical integration
+import GSL
+
+quad f a b = fst $ integrateQAGS 1E-9 100 f a b  
+
+-- A multiple integral can be easily defined using partial application
+quad2 f a b g1 g2 = quad h a b
+    where h x = quad (f x) (g1 x) (g2 x)
+
+volSphere r = 8 * quad2 (\x y -> sqrt (r*r-x*x-y*y)) 
+                        0 r (const 0) (\x->sqrt (r*r-x*x))
+
+main = do
+    print $ quad (\x -> 4/(x^2+1)) 0 1
+    print pi
+    print $ volSphere 2.5
+    print $ 4/3*pi*2.5**3