Unbias a random generator: Difference between revisions

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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.
-=={{header|J}}==
+=={{header|D}}==
+<lang d>import std.stdio, std.random;
+bool biased(int n) {
+    return uniform(0.0, 1.0) < (1.0 / n);
+}
+bool unbiased(int n) {
+    bool a, b;
+    do {
+        a = biased(n);
+        b = biased(n);
+    } while (a == b);
+    return a;
+}
+void main() {
+    int M = 50_000;
+    foreach (n; 3 .. 7) {
+        int c1, c2;
+        foreach (i; 0 .. M) {
+            c1 += biased(n);
+            c2 += unbiased(n);
+        }
+        writefln("%d: %2.2f%%  %2.2f%%", n, 100.0*c1/M, 100.0*c2/M);
+    }
+}</lang>
+Output:
+<pre>3: 33.12%  50.15%
+: 25.13%  50.02%
+: 19.61%  50.01%
+: 16.70%  49.98%</pre>
+=={{header|J}}==
 <lang j>randN=: 0 = ?
 unbiased=: i.@# { ::$: 2 | 0 3 -.~ _2 #.\ 4&* randN@# ]</lang>