Unbias a random generator: Difference between revisions
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m (→{{header|C}}: pretty silly to show both n and n% when denom is power of 10) |
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The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN. |
The actual unbiasing should be done by generating two numbers at a time from randN and only returning a 1 or 0 if they are different. As long as you always return the first number or always return the second number, the probabilities discussed above should take over the biased probability of randN. |
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=={{header|Ada}}== |
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<lang Ada>with Ada.Text_IO; with Ada.Numerics.Discrete_Random; |
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procedure Bias_Unbias is |
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Modulus: constant Integer := 60; -- lcm of {3,4,5,6} |
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type M is mod Modulus; |
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package Rand is new Ada.Numerics.Discrete_Random(M); |
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Gen: Rand.Generator; |
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subtype Bit is Integer range 0 .. 1; |
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function Biased_Bit(Bias_Base: Integer) return Bit is |
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begin |
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if (Integer(Rand.Random(Gen))* Bias_Base) / Modulus > 0 then |
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return 0; |
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else |
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return 1; |
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end if; |
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end Biased_Bit; |
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function Unbiased_Bit(Bias_Base: Integer) return Bit is |
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A, B: Bit := 0; |
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begin |
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while A = B loop |
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A := Biased_Bit(Bias_Base); |
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B := Biased_Bit(Bias_Base); |
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end loop; |
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return A; |
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end Unbiased_Bit; |
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package FIO is new Ada.Text_IO.Float_IO(Float); |
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Counter_B, Counter_U: Natural; |
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Number_Of_Samples: constant Natural := 10_000; |
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begin |
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Rand.Reset(Gen); |
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Ada.Text_IO.Put_Line(" I Biased% UnBiased%"); |
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for I in 3 .. 6 loop |
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Counter_B := 0; |
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Counter_U := 0; |
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for J in 1 .. Number_Of_Samples loop |
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Counter_B := Counter_B + Biased_Bit(I); |
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Counter_U := Counter_U + Unbiased_Bit(I); |
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end loop; |
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Ada.Text_IO.Put(Integer'Image(I)); |
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FIO.Put(100.0 * Float(Counter_B) / Float(Number_Of_Samples), 4, 2, 0); |
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FIO.Put(100.0 * Float(Counter_U) / Float(Number_Of_Samples), 5, 2, 0); |
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Ada.Text_IO.New_Line; |
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end loop; |
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end Bias_Unbias;</lang> |
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Output:<pre> I Biased% UnBiased% |
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3 32.87 49.80 |
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4 24.49 50.22 |
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5 19.73 50.05 |
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6 16.75 50.19 |
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</pre> |
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=={{header|C}}== |
=={{header|C}}== |
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<lang C>#include <stdio.h> |
<lang C>#include <stdio.h> |
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