September Morn Update

Task/Percolation-Mean-run-density/Factor/percolation-mean-run-density.factor

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+USING: formatting fry io kernel math math.ranges math.statistics
+random sequences ;
+IN: rosetta-code.mean-run-density
+
+: rising? ( ? ? -- ? ) [ f = ] [ t = ] bi* and ;
+
+: count-run ( n ? ? -- m ? )
+    2dup rising? [ [ 1 + ] 2dip ] when nip ;
+
+: runs ( n p -- n )
+    [ 0 f ] 2dip '[ random-unit _ < count-run ] times drop ;
+
+: rn ( n p -- x ) over [ runs ] dip /f ;
+
+: sim ( n p -- avg )
+    [ 1000 ] 2dip [ rn ] 2curry replicate mean ;
+
+: theory ( p -- x ) 1 over - * ;
+
+: result ( n p -- )
+    [ swap ] [ sim ] [ nip theory ] 2tri 2dup - abs
+    "%.1f  %-5d  %.4f  %.4f  %.4f\n" printf ;
+
+: test ( p -- )
+    { 100 1,000 10,000 } [ swap result ] with each nl ;
+
+: header ( -- )
+    "1000 tests each:\np    n      K       p(1-p)  diff" print ;
+
+: main ( -- ) header .1 .9 .2 <range> [ test ] each ;
+
+MAIN: main

Task/Percolation-Mean-run-density/Phix/percolation-mean-run-density.phix

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+function run_test(atom p, integer len, runs)
+    integer count = 0
+    for r=1 to runs do
+        bool v, pv = false
+        for l=1 to len do
+            v = rnd()<p
+            count += pv<v
+            pv = v
+        end for
+    end for
+    return count/runs/len
+end function
+
+procedure main()
+    printf(1,"Running 1000 tests each:\n")
+    printf(1," p        n  K       p(1-p)       delta\n")
+    printf(1,"--------------------------------------------\n")
+    for ip=1 to 10 by 2 do
+        atom p = ip/10,
+             p1p = p*(1-p)
+        integer n = 100
+        while n<=100000 do
+            atom K = run_test(p, n, 1000)
+            printf(1,"%.1f  %6d  %6.4f  %6.4f  %+7.4f (%+5.2f%%)\n",
+                   {p, n, K, p1p, K-p1p, (K-p1p)/p1p*100})
+            n *= 10
+        end while
+        printf(1,"\n")
+    end for
+end procedure
+main()

Task/Percolation-Mean-run-density/Racket/percolation-mean-run-density-2.rkt

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+/* REXX */
+Numeric Digits 20
+Call random(,12345) /* make the run reproducable */
+pList = '.1 .3 .5 .7 .9'
+nList = '1e2 1e3 1e4 1e5'
+t     = 100
+Do While plist<>''
+  Parse Var plist p plist
+  theory=p*(1-p)
+  Say ' '
+  Say 'p:' format(p,2,4)'  theory:'format(theory,2,4)'  t:'format(t,4)
+  Say '         n          sim     sim-theory'
+  nl=nlist
+  Do While nl<>''
+    Parse Var nl n nl
+    sum=0
+    Do i=1 To t
+      run=0
+      Do j=1 To n
+        one=random(1000)<p*1000
+        If one & (run=0) Then
+          sum=sum+1
+        run=one
+        End
+      End
+    sim=sum/(n*100)
+    Say format(n,10)'        ' format(sim,2,4)' 'format(sim-theory,2,6)
+    End
+  End