lib/polynomials.rb in polynomials-0.1.6 vs lib/polynomials.rb in polynomials-0.1.7

@@ -36,11 +36,11 @@
       new_function.terms.reject! { |_,t| t.coefficient == 0 }
     return new_function
   end
 
   def roots
-    if terms.keys.none?(&:zero?)
+    if !terms.empty? and terms.keys.none?(&:zero?)
       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]
@@ -59,11 +59,10 @@
   def local_extrema
     derivative = self.derivative
     max_min_extremum =  Hash.new { |hash,key| hash[key] = Set.new }
     possible_extrema = derivative.roots.sort
     unless possible_extrema.empty?
-
       samples = ([possible_extrema.first - 1] + possible_extrema.sort + [possible_extrema.last + 1]).each_cons(2).map do |before,after|
         (before + after)/2
       end
 
       possible_extrema.zip(samples.each_cons(2)).each do |pe,(after,before)|
@@ -75,24 +74,21 @@
     end
     return max_min_extremum
   end
 
   def curvature_behaviour
-    if degree < 2
-      return {}
-    else
-      extrema = self.derivative.extrema
-      curvature_behaviour = Hash.new {|h,k|h[k]=Set.new}
-      extrema.values.inject(&:|).sort.each_cons(2) do |start_point,end_point|
-        curvature_behaviour[AfterextremaCurvatureMapping[extrema.find { |k,v| v.include?(start_point) }.first]] << Range.new(start_point,end_point)
-      end
+    hash = Hash.new {|h,k|h[k]=Set.new}
+    extrema = self.derivative.extrema
+    extrema.values.inject(Set[],&:|).sort.each_cons(2).inject(hash) do |curvature_behaviour,(start_point,end_point)|
+      kind_of_curvature = AfterextremaCurvatureMapping[extrema.find { |k,v| v.include?(start_point) }.first]
+      curvature_behaviour[kind_of_curvature] << Range.new(start_point,end_point)
+      curvature_behaviour
     end
-    return curvature_behaviour
   end
 
   def degree
-    self.terms.keys.max
+    self.terms.keys.max || 0
   end
 
   def to_s
     terms.delete_if { |_,t| t.coefficient.zero? }.sort_by { |_,t| -t.exponent }.inject("") do |string,(_,term)|
       string << term.to_s
@@ -105,12 +101,14 @@
   end
 
   def extrema
     extrema = local_extrema
     a = self.terms[self.degree].coefficient
-    max_or_min = (self.degree.even? ? [1,1] : [-1,1]).map { |n| (n * a)/a.abs  }
-    extrema[MinMaxMapping[max_or_min.first]] << -1.0/0
-    extrema[MinMaxMapping[max_or_min.last]] << 1.0/0
+    unless self.degree == 0
+      max_or_min = (self.degree.even? ? [1,1] : [-1,1]).map { |n| (n * a)/a.abs  }
+      extrema[MinMaxMapping[max_or_min.first]] << -1.0/0
+      extrema[MinMaxMapping[max_or_min.last]] << 1.0/0
+    end
     return extrema
   end
 
  private