lib/utils/mathutil.rb in stella-0.5.3 vs lib/utils/mathutil.rb in stella-0.5.4

@@ -4,18 +4,21 @@
   
   def self.variance(population)
     n = 0
     mean = 0.0
     s = 0.0
+    
     population.each { |x|
       n = n + 1
       delta = (x - mean).to_f
       mean = (mean + (delta / n)).to_f
       s = (s + delta * (x - mean)).to_f
     }
     
-    return s / n
+    s / n
+  rescue => ex
+    0.0
   end
 
   # calculate the standard deviation of a population
   # accepts: an array, the population
   # returns: the standard deviation
@@ -41,38 +44,48 @@
 
     ##
     # Sum of all the elements of the Enumerable
 
     def sum
-        return self.inject(0) { |acc, i| acc + i }
+        return 0 if !self || self.empty?
+        self.inject(0) { |acc, i| acc.to_f + i.to_f }
     end
 
     ##
     # Average of all the elements of the Enumerable
     #
     # The Enumerable must respond to #length
 
     def average
-        return self.sum / self.length.to_f
+      return 0 unless self
+      self.sum / self.length.to_f
+    rescue => ex
+      0.0
     end
 
     ##
     # Sample variance of all the elements of the Enumerable
     #
     # The Enumerable must respond to #length
 
     def sample_variance
-        avg = self.average
-        sum = self.inject(0) { |acc, i| acc + (i - avg) ** 2 }
-        return (1 / self.length.to_f * sum)
+      return 0 unless self
+      avg = self.average
+      sum = self.sum
+      (1 / self.length.to_f * sum)
+    rescue => ex
+      0.0
     end
 
     ##
     # Standard deviation of all the elements of the Enumerable
     #
     # The Enumerable must respond to #length
 
     def standard_deviation
-        return Math.sqrt(self.sample_variance)
+      return 0 unless self
+      Math.sqrt(self.sample_variance)
+    rescue => ex
+      0.0
     end
 
 end
\ No newline at end of file