Implement div with Number (#180)

* Implement div with Number

* Exclude tests for old Julia version

Author: blegat

src/division.jl

@@ -1,5 +1,16 @@
 export divides
 
+Base.round(t::AbstractTermLike; args...) = term(round(coefficient(t); args...), monomial(t))
+function Base.round(p::APL; args...)
+    # round(0.1) is zero so we cannot use SortedUniqState
+    polynomial!(round.(terms(p); args...), SortedState())
+end
+
+Base.div(t::AbstractTermLike, α::Number, args...) = term(div(coefficient(t), α, args...), monomial(t))
+function Base.div(p::APL, α::Number, args...)
+    polynomial!(div.(terms(p), α, args...), SortedState())
+end
+
 """
     divides(t1::AbstractTermLike, t2::AbstractTermLike)
 

src/polynomial.jl

@@ -403,12 +403,6 @@ function mapcoefficientsnz(f::Function, p::AbstractPolynomialLike)
 end
 mapcoefficientsnz(f::Function, t::AbstractTermLike) = term(f(coefficient(t)), monomial(t))
 
-Base.round(t::AbstractTermLike; args...) = term(round(coefficient(t); args...), monomial(t))
-function Base.round(p::AbstractPolynomialLike; args...)
-    # round(0.1) is zero so we cannot use SortedUniqState
-    polynomial!(round.(terms(p); args...), SortedState())
-end
-
 """
     deg_num_leading_terms(p::AbstractPolynomialLike, var)
 

test/division.jl

@@ -4,6 +4,17 @@ using Combinatorics
 using MultivariatePolynomials
 const MP = MultivariatePolynomials
 
+function div_number_test()
+    Mod.@polyvar x
+    @test div(2x, 2) == x
+    @test div(6x + 9x^2, 3) == 2x + 3x^2
+    @test div(6x + 9x^2, 4) == x + 2x^2
+    if VERSION >= v"1.6"
+        @test div(10x^3, 4, RoundUp) == 3x^3
+        @test div(6x + 9x^2, 4, RoundUp) == 2x + 3x^2
+    end
+end
+
 function gcd_lcm_test()
     Mod.@polyvar x y z
     @test gcd(x*y, y) == y
@@ -278,6 +289,9 @@ function extracted_variable_test()
 end
 
 @testset "Division" begin
+    @testset "div by number" begin
+        div_number_test()
+    end
     @testset "GCD and LCM" begin
         gcd_lcm_test()
     end