Random numbers: Difference between revisions

=={{header|Lobster}}==

Uses built-in <code>rnd_gaussian</code>

<lang Lobster>

let mean = 1.0

let stdv = 0.5

let count = 1000

// stats computes a running mean and variance

// See Knuth TAOCP vol 2, 3rd edition, page 232

def stats(xs: [float]) -> float, float: // variance, mean

var M = xs[0]

var S = 0.0

var n = 1.0

for(xs.length - 1) i:

let x = xs[i + 1]

n = n + 1.0

let mm = (x - M)

M += mm / n

S += mm * (x - M)

return (if n > 0.0: S / n else: 0.0), M

def test_random_normal() -> [float]:

rnd_seed(floor(seconds_elapsed() * 1000000))

let r = vector_reserve(typeof return, count)

for (count):

r.push(rnd_gaussian() * stdv + mean)

let cvar, cmean = stats(r)

let cstdv = sqrt(cvar)

print concat_string(["Mean: ", string(cmean), ", Std.Deviation: ", string(cstdv)], "")

test_random_normal()

</lang>