Merge pull request #8 from jverzani/patch-3

modify degree for Poly([0.0]); polyder

Author: Keno

src/Polynomials.jl

@@ -191,15 +191,15 @@ function degree{T}(p::Poly{T})
             return i
         end
     end
-    return -1
+    return 0
 end
 
 function divrem{T, S}(num::Poly{T}, den::Poly{S})
     if num.var != den.var
         error("Polynomials must have same variable")
     end
     m = degree(den)
-    if m < 0
+    if m == 0 && den[0] == 0
         throw(DivideError())
     end
     R = typeof(one(T)/one(S))
@@ -278,7 +278,7 @@ function polyder{T}(p::Poly{T}, order::Int=1)
     else
         p2 = Poly(Array(T, n-order), p.var)
         for i = order:n-1
-            p2[i-order] = p[i] * factorial(i)/factorial(i-order)
+            p2[i-order] = p[i] * prod((i-order+1):i)
         end
         return p2
     end

test/tests.jl

@@ -32,6 +32,8 @@ sprint(show, pNULL)
 @test pNULL^3 == pNULL
 @test pNULL*pNULL == pNULL
 
+@test map(Polynomials.degree, [pNULL,p0,p1,p2,p3,p4,p5,pN,pR,p1000]) == [0,0,0,1,2,3,4,4,2,999] 
+
 @test polyval(pN, -.125) == 276.9609375
 @test polyval(pNULL, 10) == 0
 @test polyval(p0, -10) == 0