lib/polynomials.rb in polynomials-0.1.2 vs lib/polynomials.rb in polynomials-0.1.4

@@ -41,13 +41,13 @@
       yield new_function, term
     end
     return new_function
   end
 
-  def nulls
+  def roots
     if terms.keys.none?(&:zero?)
-      self.alter { |nf, term| nf.terms[term.exponent-1].coefficient = term.coefficient }.nulls << 0.0
+      self.alter { |nf, term| nf.terms[term.exponent-1].coefficient = term.coefficient }.roots << 0.0
     else
       case self.degree
       when 1
         Set[-self.terms[0].coefficient / self.terms[1].coefficient]
       when 2
@@ -62,21 +62,23 @@
     end
   end
 
   def local_extremums
     derivative = self.derivative
-    possible_extremums = derivative.nulls.sort
     max_min_extremum =  Hash.new { |hash,key| hash[key] = Set.new }
+    unless derivative.degree == 0 
+      possible_extremums = derivative.roots.sort
 
-    samples = ([possible_extremums.first - 1] + possible_extremums.sort + [possible_extremums.last + 1]).each_cons(2).map do |before,after|
-      (before + after)/2
-    end
+      samples = ([possible_extremums.first - 1] + possible_extremums.sort + [possible_extremums.last + 1]).each_cons(2).map do |before,after|
+        (before + after)/2
+      end
 
-    possible_extremums.zip(samples.each_cons(2)).each do |pe,(after,before)|
-      yafter = derivative.calculate(after)
-      ybefore = derivative.calculate(before)
-      kind_of_extremum = NegPosMinMaxExtremumMapping[[yafter/yafter.abs,ybefore/ybefore.abs]]
-      max_min_extremum[kind_of_extremum] << pe if kind_of_extremum
+      possible_extremums.zip(samples.each_cons(2)).each do |pe,(after,before)|
+        yafter = derivative.calculate(after)
+        ybefore = derivative.calculate(before)
+        kind_of_extremum = NegPosMinMaxExtremumMapping[[yafter/yafter.abs,ybefore/ybefore.abs]]
+        max_min_extremum[kind_of_extremum] << pe if kind_of_extremum
+      end
     end
     return max_min_extremum
   end
 
   def curvature_behaviour