adjust isapprox to match usage with Vector{T}

Author: jverzani

Project.toml

@@ -3,7 +3,7 @@ name = "Polynomials"
 uuid = "f27b6e38-b328-58d1-80ce-0feddd5e7a45"
 license = "MIT"
 author = "JuliaMath"
-version = "1.1.0"
+version = "1.1.1"
 
 [deps]
 Intervals = "d8418881-c3e1-53bb-8760-2df7ec849ed5"

src/common.jl

@@ -561,26 +561,28 @@ Base.:(==)(n::Number, p::AbstractPolynomial) = p == n
 function Base.isapprox(p1::AbstractPolynomial{T},
     p2::AbstractPolynomial{S};
     rtol::Real = (Base.rtoldefault(T, S, 0)),
-    atol::Real = 0,) where {T,S}
+                       atol::Real = 0,) where {T,S}
+    
     p1, p2 = promote(p1, p2)
     check_same_variable(p1, p2)  || error("p1 and p2 must have same var")
-    p1t = truncate(p1; rtol = rtol, atol = atol)
-    p2t = truncate(p2; rtol = rtol, atol = atol)
-    if length(p1t) ≠ length(p2t)
-        return false
+
+    # copy over from abstractarray.jl
+    Δ  = norm(p1-p2)
+    if isfinite(Δ)
+        return Δ <= max(atol, rtol*max(norm(p1), norm(p2)))
+    else
+        for i in 0:max(degree(p1), degree(p2))
+            isapprox(p1[i], p2[i]; rtol=rtol, atol=atol) || return false
+        end
+        return true
     end
-    isapprox(coeffs(p1t), coeffs(p2t), rtol = rtol, atol = atol)
 end
 
-function Base.isapprox(p1::AbstractPolynomial{T},
+function Base.isapprox(p1::P,
                        n::S;
                        rtol::Real = (Base.rtoldefault(T, S, 0)),
-                       atol::Real = 0,) where {T,S}
-    p1t = truncate(p1, rtol = rtol, atol = atol)
-    if length(p1t) != 1
-        return false
-    end
-    isapprox(coeffs(p1t), [n], rtol = rtol, atol = atol)
+                       atol::Real = 0,) where {T,S, P<:AbstractPolynomial{T}}
+    return isapprox(p1, ⟒(P){T}(n,p1.var))
 end
 
 Base.isapprox(n::S,

test/StandardBasis.jl

@@ -230,6 +230,17 @@ end
         @test P([0.5]) + 2 == P([2.5])
         @test 2 - P([0.5]) == P([1.5])
 
+        # check ≈ for P matches usage for Vector{T} (possibly padded with trailing zeros)
+        @test (P([NaN]) ≈ P([NaN]))               == ([NaN] ≈ [NaN]) # false
+        @test (P([NaN]) ≈ NaN)                    == (false)
+        @test (P([Inf]) ≈ P([Inf]))               == ([Inf] ≈ [Inf]) # true
+        @test (P([Inf]) ≈ Inf)                    == (true)
+        @test (P([1,Inf]) ≈ P([0,Inf]))           == ([1,Inf] ≈ [0,Inf]) # false 
+        @test (P([1,NaN,Inf]) ≈ P([0,NaN, Inf]))  == ([1,NaN,Inf] ≈ [0,NaN, Inf]) #false  
+        @test (P([eps(), eps()]) ≈ P([0,0]))      == ([eps(), eps()] ≈ [0,0]) # false
+        @test (P([1,eps(), 1]) ≈ P([1,0,1]))      == ([1,eps(), 1] ≈ [1,0,1]) # true
+        @test (P([1,2]) ≈ P([1,2,eps()]))         == ([1,2,0] ≈ [1,2,eps()])
+
 
         # check how ==, ===, isapprox ignore variable mismatch when constants are involved, issue #217, issue #219
         @test zero(P, :x) == zero(P, :y)