Weighted Random number about a Center

[dcromley]

This reminded me of my "Bates distribution" program in my files, which I ported: (Very good in QB64.)

Code: (Select All)

_Title "Bates distribution" ' dcromley
' https://en.wikipedia.org/wiki/Bates_distribution
Option _Explicit
Screen _NewImage(1024, 768, 256)
Color 0, 15
Cls
Dim Shared n000 as Long, yfactor
Dim exp2
n000 = 10 ^ 6 ' big number

For exp2 = 0 To 3 ' for 1,2,4,8
  Dim nrnds
  nrnds = 2 ^ exp2 ' now 1,2,4,8
  yfactor = 768 * 1024 / n000 / 5 ' height
  doDist (nrnds) ' plot a distribution
Next exp2

Locate 37, 62: Print "1 rnd"
Locate 28, 62: Print "2 rnds"
Locate 21, 62: Print "4 rnds"
Locate 10, 62: Print "8 rnds"
While InKey$ = "": Wend: System

Sub doDist (nrnds) ' plot distribution
  Dim i as Long, x, r, a(1023)
  For i = 1 To n000 ' fill array with counts
    r = Int(rand(nrnds) / nrnds * 1024) ' random number 0 to 1023
    a(r) = a(r) + 1 ' count of hits
  Next i
  For x = 0 To 1022 ' plot array
    Line (x, 767 - a(x) * yfactor)-(x + 1, 767 - a(x + 1) * yfactor)
  Next x
End Sub

Function rand (kn) ' sum of kn random numbers 0 to 1
  Dim i, ret
  For i = 1 To kn
    ret = ret + Rnd
  Next i
  rand = ret
End Function