Fix scala Erf & add Expm1

scala/SConscript

@@ -3,7 +3,7 @@ PACKAGE_NAME = "picomath"
 #This is kind of a hack to deal with the lack of scons support for the
 #autogenerated class files from scala that don't directly map to
 #.scala files (i.e. Erf$.class)
-bld = Builder(action = 'jar cfm picomath.jar MANIFEST classes/Erf$.class -C classes Erf.class classes/Main$.class -C classes Main.class')
+bld = Builder(action = 'cd scala;jar cfm picomath.jar MANIFEST classes/Erf$.class -C classes Erf.class classes/Main$.class -C classes Main.class -C classes Expm1.class classes/Expm1$.class')
 env = Environment(JAVAC = "scalac", JAVASUFFIX=".scala")
 env.Append(BUILDERS = {'hobojar' : bld})
 env.Java('classes', 'src')

scala/src/Erf.scala

@@ -1,5 +1,6 @@
 import scala.math
 
+//Calculates the error function using Horner’s method.
 class Erf {
   // constants
   val a1: Double =  0.254829592;
@@ -11,7 +12,7 @@ class Erf {
 
   def erf(x: Double): Double =  {
         // Save the sign of x
-        val sign = if (x < 0) 1 else 0
+        val sign = if (x < 0) -1 else 1
         val absx =  math.abs(x)
 
         // A&S formula 7.1.26

scala/src/Expm1.scala

@@ -0,0 +1,14 @@
+import scala.math
+
+//Calculates the value of the natural logarithm base (e) raised to the power of x, minus 1.
+class Expm1 {
+    def expm1(x: Double): Double = {
+        if (math.abs(x) < 1e-5) {
+            return x + 0.5*x*x;
+        } else {
+            return math.exp(x) - 1.0;
+        }
+    }
+}
+
+object Expm1 extends Expm1

scala/src/Main.scala

@@ -11,9 +11,9 @@ object Main extends App {
       val x: Double = a.apply(1).toDouble;
       a.apply(0) match {
         case "erf" =>  println(Erf.erf(x));
-        case _ => println("Unknown function: " + a.apply(0));
+        case "expm1" => println(Expm1.expm1(x));
+        case _ => { println("Unknown function: " + a.apply(0)); return;}
       }
-      return;
     }
   }
 }