Random Numbers

Simba provides various methods to generate random numbers with different distributions.

The following methods are:

Random:

Random generates approximately uniform distribution.

function Random: Double; overload;
function Random(l: Int64): Int64; overload;
function Random(min, max: Double): Double; overload;
function Random(min, max: Int64): Int64; overload;

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RandomLeft:

RandomLeft generates weighted numbers towards Lo

function RandomLeft(Lo, Hi: Double): Double; overload;
function RandomLeft(Lo, Hi: Int64): Int64; overload;

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RandomRight:

RandomRight generates weighted numbers towards Hi

function RandomRight(Lo, Hi: Double): Double; overload;
function RandomRight(Lo, Hi: Int64): Int64; overload;

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RandomMean:

RandomMean generates weighted numbers towards the mean of Lo..Hi

function RandomMean(Lo, Hi: Double): Double; overload;
function RandomMean(Lo, Hi: Int64): Int64; overload;

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RandomMode:

RandomMode generates weighted numbers towards Mode within Lo..Hi

function RandomMode(Mode, Lo, Hi: Double): Double; overload;
function RandomMode(Mode, Lo, Hi: Int64): Int64; overload;

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You can also write a small script to show the spread.

This shows the spread of 1000000 calls of RandomLeft(0, 10):

const
  SampleCount = 1000000;
  Range = 10;

var
  Hits: TIntegerArray;
  I: Integer;
begin
  SetLength(Hits, Range);
  for I := 1 to SampleCount do
    Hits[RandomLeft(0, Range)] += 1;

  for I := 0 to High(Hits) do
    WriteLn(I, ' was rolled ', Hits[I], ' times (', Round((Hits[I] / SampleCount) * 100, 4), ' percent)');
end;

Output

0 was rolled 382874 times (38.2874 percent)
1 was rolled 300305 times (30.0305 percent)
2 was rolled 183102 times (18.3102 percent)
3 was rolled 88345 times (8.8345 percent)
4 was rolled 32958 times (3.2958 percent)
5 was rolled 9715 times (0.9715 percent)
6 was rolled 2195 times (0.2195 percent)
7 was rolled 442 times (0.0442 percent)
8 was rolled 60 times (0.006 percent)
9 was rolled 4 times (0.0004 percent)