Data commit

Task/Percolation-Mean-run-density/Pascal/percolation-mean-run-density.pas

@@ -0,0 +1,52 @@
+{$MODE objFPC}//for using result,parameter runs becomes for variable..
+uses
+  sysutils;//Format
+const
+  MaxN = 100*1000;
+
+function run_test(p:double;len,runs: NativeInt):double;
+var
+   x, y, i,cnt : NativeInt;
+Begin
+  result := 1/ (runs * len);
+  cnt := 0;
+  for  runs := runs-1 downto 0 do
+  Begin
+    x := 0;
+    y := 0;
+    for i := len-1 downto 0 do
+    begin
+      x := y;
+      y := Ord(Random() < p);
+      cnt := cnt+ord(x < y);
+    end;
+  end;
+  result := result *cnt;
+end;
+
+//main
+var
+  p, p1p, K : double;
+  ip, n : nativeInt;
+Begin
+  randomize;
+  writeln( 'running 1000 tests each:'#13#10,
+    ' p      n      K     p(1-p)   diff'#13#10,
+    '-----------------------------------------------');
+  ip:= 1;
+  while ip < 10 do
+  Begin
+     p := ip / 10;
+     p1p := p * (1 - p);
+     n := 100;
+     While n <= MaxN do
+     Begin
+       K := run_test(p, n, 1000);
+       writeln(Format('%4.1f %6d  %6.4f  %6.4f %7.4f (%5.2f %%)',
+         [p, n, K, p1p, K - p1p, (K - p1p) / p1p * 100]));
+       n := n*10;
+     end;
+     writeln;
+     ip := ip+2;
+   end;
+end.