Monte Carlo methods: Difference between revisions
Content added Content deleted
(→JS ES6) |
(→{{header|Haskell}}: Added a variant using foldM and dropping sqrt) |
||
| Line 1,272: | Line 1,272: | ||
=={{header|Haskell}}== |
=={{header|Haskell}}== |
||
<lang haskell> |
<lang haskell>import System.Random |
||
| ⚫ | |||
import Control.Monad |
import Control.Monad |
||
| Line 1,283: | Line 1,282: | ||
let dist :: Double |
let dist :: Double |
||
dist = sqrt (rand_x*rand_x + rand_y*rand_y) |
dist = sqrt (rand_x*rand_x + rand_y*rand_y) |
||
return (if dist < 1 then 1 else 0) |
return (if dist < 1 then 1 else 0)</lang> |
||
{{Out}} |
|||
</lang> |
|||
Example: |
<pre>Example: |
||
Prelude System.Random Control.Monad> get_pi 10000 |
Prelude System.Random Control.Monad> get_pi 10000 |
||
3.1352 |
3.1352 |
||
| Line 1,291: | Line 1,290: | ||
3.15184 |
3.15184 |
||
Prelude System.Random Control.Monad> get_pi 1000000 |
Prelude System.Random Control.Monad> get_pi 1000000 |
||
3.145024 |
3.145024</pre> |
||
Or, using foldM, and dropping sqrt: |
|||
<lang haskell>import Control.Monad (foldM, (>=>)) |
|||
| ⚫ | |||
monteCarloPi :: Int -> IO Double |
|||
monteCarloPi n = do |
|||
m <- foldM go 0 [1 .. n] |
|||
return (4 * fromIntegral m / fromIntegral n) |
|||
where |
|||
rnd = randomRIO (0, 1) :: IO Double |
|||
f x y |
|||
| 1 > x ** 2 + y ** 2 = succ |
|||
| otherwise = id |
|||
go a x = do |
|||
rx <- rnd |
|||
ry <- rnd |
|||
return $ f rx ry a |
|||
main :: IO () |
|||
main = |
|||
mapM_ |
|||
(monteCarloPi >=> print) |
|||
[1000, 10000, 100000, 1000000]</lang> |
|||
{{Out}} |
|||
For example: |
|||
<pre>3.244 |
|||
3.1116 |
|||
3.14116 |
|||
3.141396</pre> |
|||
=={{header|HicEst}}== |
=={{header|HicEst}}== |
||