Data commit

Task/Percolation-Mean-run-density/Tcl/percolation-mean-run-density.tcl

@@ -0,0 +1,33 @@
+proc randomString {length probability} {
+    for {set s ""} {[string length $s] < $length} {} {
+	append s [expr {rand() < $probability}]
+    }
+    return $s
+}
+
+# By default, [regexp -all] gives the number of times that the RE matches
+proc runs {str} {
+    regexp -all {1+} $str
+}
+
+# Compute the mean run density
+proc mrd {t p n} {
+    for {set i 0;set total 0.0} {$i < $t} {incr i} {
+	set run [randomString $n $p]
+	set total [expr {$total + double([runs $run])/$n}]
+    }
+    return [expr {$total / $t}]
+}
+
+# Parameter sweep with nested [foreach]
+set runs 500
+foreach p {0.10 0.30 0.50 0.70 0.90} {
+    foreach n {1024 4096 16384} {
+	set theory [expr {$p * (1 - $p)}]
+	set sim [mrd $runs $p $n]
+	set diffpc [expr {abs($theory-$sim)*100/$theory}]
+	puts [format "t=%d, p=%.2f, n=%5d, p(1-p)=%.3f, sim=%.3f, delta=%.2f%%" \
+		      $runs $p $n $theory $sim $diffpc]
+    }
+    puts ""
+}