Merge pull request #245 from jverzani/issue_240b

closes #240.

Author: jverzani

.travis.yml

@@ -11,6 +11,7 @@ julia:
   - 1.2
   - 1.3
   - 1.4
+  - 1.5
   - nightly
 
 notifications:

src/Polynomials.jl

@@ -18,6 +18,7 @@ include("polynomials/Polynomial.jl")
 include("polynomials/ImmutablePolynomial.jl")
 include("polynomials/SparsePolynomial.jl")
 include("polynomials/LaurentPolynomial.jl")
+include("polynomials/ngcd.jl")
 
 include("polynomials/ChebyshevT.jl")
 

src/common.jl

@@ -536,11 +536,17 @@ Polynomial(4.0 - 6.0*x + 2.0*x^2)
 
 ```
 """
-function Base.gcd(p1::AbstractPolynomial{T}, p2::AbstractPolynomial{S};
-                  atol::Real=zero(real(promote_type(T,S))),
-                  rtol::Real=Base.rtoldefault(real(promote_type(T,S)))
-                  ) where {T,S}
-    r₀, r₁ = promote(p1, p2)
+function Base.gcd(p1::AbstractPolynomial{T}, p2::AbstractPolynomial{S}; kwargs...) where {T,S}
+    gcd(promote(p1, p2)...; kwargs...)
+end
+
+function Base.gcd(p1::P, p2::Q;
+                  atol::Real=zero(real(T)),
+                  rtol::Real=Base.rtoldefault(real(T))
+                  ) where {T, P <: AbstractPolynomial{T}, Q <: AbstractPolynomial{T}}
+
+
+    r₀, r₁ = p1, p2
     iter = 1
     itermax = length(r₁)
 

src/polynomials/LaurentPolynomial.jl

@@ -426,3 +426,20 @@ function integrate(p::P, k::S) where {T, P<: LaurentPolynomial{T}, S<:Number}
     return ⟒(P)(as, m:n, p.var)
 
 end
+
+
+function Base.gcd(p::LaurentPolynomial{T}, q::LaurentPolynomial{T}, args...; kwargs...) where {T}
+    mp, Mp = extrema(p)
+    mq, Mq = extrema(q)
+    if mp < 0 || mq < 0
+        throw(ArgumentError("GCD is not defined when there are `x⁻¹` terms"))
+    end
+
+    degree(p) == 0 && return iszero(p) ? q : one(q)
+    degree(q) == 0 && return iszero(q) ? p : one(p)
+    check_same_variable(p,q) || throw(ArgumentError("p and q have different symbols"))
+    
+    pp, qq = convert(Polynomial, p), convert(Polynomial, q)
+    u = gcd(pp, qq, args..., kwargs...)
+    return LaurentPolynomial(coeffs(u), p.var)
+end