--- a/progs/re3a.scala	Thu Jul 25 14:39:37 2019 +0100
+++ b/progs/re3a.scala	Sun Jul 28 01:00:41 2019 +0100
@@ -9,7 +9,7 @@
 case class NTIMES(r: Rexp, n: Int) extends Rexp 
 case class UPNTIMES(r: Rexp, n: Int) extends Rexp 
 
-// nullable function: tests whether the regular 
+// the nullable function: tests whether the regular 
 // expression can recognise the empty string
 def nullable (r: Rexp) : Boolean = r match {
   case ZERO => false
@@ -22,7 +22,7 @@
   case UPNTIMES(r: Rexp, n: Int) => true
 }
 
-// derivative of a regular expression w.r.t. a character
+// the derivative of a regular expression w.r.t. a character
 def der (c: Char, r: Rexp) : Rexp = r match {
   case ZERO => ZERO
   case ONE => ZERO
@@ -58,20 +58,20 @@
 }
 
 
-// derivative w.r.t. a string (iterates der)
+// the derivative w.r.t. a string (iterates der)
 def ders (s: List[Char], r: Rexp) : Rexp = s match {
   case Nil => r
   case c::s => ders(s, simp(der(c, r)))
 }
 
 
-// main matcher function
-def matcher(r: Rexp, s: String) : Boolean = nullable(ders(s.toList, r))
+// the main matcher function
+def matches(r: Rexp, s: String) : Boolean = nullable(ders(s.toList, r))
 
-//one or zero
+// one or zero
 def OPT(r: Rexp) = ALT(r, ONE)
 
-//evil regular expressions
+// evil regular expressions
 def EVIL1(n: Int) = SEQ(NTIMES(OPT(CHAR('a')), n), NTIMES(CHAR('a'), n))
 val EVIL2 = SEQ(STAR(STAR(CHAR('a'))), CHAR('b'))
 val EVIL3 = SEQ(STAR(ALT(CHAR('a'), SEQ(CHAR('a'),CHAR('a')))), CHAR('b'))
@@ -80,26 +80,18 @@
   val start = System.nanoTime()
   for (j <- 1 to i) code
   val end = System.nanoTime()
-  (end - start)/(i * 1.0e9)
+  "%.5f".format((end - start) / (i * 1.0e9))
 }
 
 
-//test: (a?{n}) (a{n})
-for (i <- 1 to 8001 by 1000) {
-  println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL1(i), "a" * i))))
+// test: (a?{n}) (a{n})
+for (i <- 0 to 8000 by 1000) {
+  println(s"$i: ${time_needed(2, matches(EVIL1(i), "a" * i))}")
 }
 
-for (i <- 1 to 8001 by 1000) {
-  println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL1(i), "a" * i))))
-}
-
-//test: (a*)* b
-for (i <- 1 to 6000001 by 500000) {
-  println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL2, "a" * i))))
-}
-
-for (i <- 1 to 6000001 by 500000) {
-  println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL2, "a" * i))))
+// test: (a*)* b
+for (i <- 0 to 6000000 by 500000) {
+  println(s"$i: ${time_needed(2, matches(EVIL2, "a" * i))}")
 }
 
 
@@ -113,8 +105,8 @@
 
 //test: (a|aa)* b
 /*
-for (i <- 1 to 7001 by 500) {
-  println(i + " " + "%.5f".format(time_needed(2, matcher(EVIL3, "a" * i ++ "c"))))
+for (i <- 0 to 100 by 10) {
+  println(s"$i: ${time_needed(2, matches(EVIL3, "a" * i ++ "c"))}")
 }
  */