Initial data commit

Task/Executable-library/Tcl/executable-library-1.tcl

@@ -0,0 +1,25 @@
+### In the file hailstone.tcl ###
+package provide hailstone 1.0
+
+proc hailstone n {
+    while 1 {
+	lappend seq $n
+	if {$n == 1} {return $seq}
+	set n [expr {$n & 1 ? $n*3+1 : $n/2}]
+    }
+}
+
+# If directly executed, run demo code
+if {[info script] eq $::argv0} {
+    set h27 [hailstone 27]
+    puts "h27 len=[llength $h27]"
+    puts "head4 = [lrange $h27 0 3]"
+    puts "tail4 = [lrange $h27 end-3 end]"
+
+    set maxlen [set max 0]
+    for {set i 1} {$i<100000} {incr i} {
+	set l [llength [hailstone $i]]
+	if {$l>$maxlen} {set maxlen $l;set max $i}
+    }
+    puts "max is $max, with length $maxlen"
+}