empty hmatrix-base

1 files changed, 24 insertions, 0 deletions

diff --git a/packages/hmatrix/examples/integrate.hs b/packages/hmatrix/examples/integrate.hs
new file mode 100644
index 0000000..3a03da6
--- /dev/null
+++ b/packages/hmatrix/examples/integrate.hs
@@ -0,0 +1,24 @@
+-- Numerical integration
+import Numeric.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 y1 y2 g1 g2 = quad h y1 y2
+  where
+    h y = quad (flip f y) (g1 y) (g2 y)
+
+volSphere r = 8 * quad2 (\x y -> sqrt (r*r-x*x-y*y)) 
+                        0 r (const 0) (\x->sqrt (r*r-x*x))
+
+-- wikipedia example
+exw = quad2 f 7 10 (const 11) (const 14)
+  where
+    f x y = x**2 + 4*y
+
+main = do
+    print $ quad (\x -> 4/(x^2+1)) 0 1
+    print pi
+    print $ volSphere 2.5
+    print $ 4/3*pi*2.5**3
+    print $ exw