fix issue with non type-stable f (#400)

* fix issue with non type-stable f

* cleaner approach?

* extension and 1.6

Author: jverzani

Project.toml

@@ -1,6 +1,6 @@
 name = "Roots"
 uuid = "f2b01f46-fcfa-551c-844a-d8ac1e96c665"
-version = "2.0.19"
+version = "2.0.20"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"
@@ -19,7 +19,6 @@ SymPyPythonCall = "bc8888f7-b21e-4b7c-a06a-5d9c9496438c"
 ChainRulesCore = "1"
 CommonSolve = "0.1, 0.2"
 ForwardDiff = "0.10"
-IntervalRootFinding = "0.5"
 SymPy = "1"
 SymPyPythonCall = "0.1,1"
 Setfield = "0.7, 0.8, 1"
@@ -37,7 +36,7 @@ Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
 BenchmarkTools = "6e4b80f9-dd63-53aa-95a3-0cdb28fa8baf"
 ChainRulesTestUtils = "cdddcdb0-9152-4a09-a978-84456f9df70a"
 ForwardDiff = "f6369f11-7733-5829-9624-2563aa707210"
-IntervalRootFinding = "d2bf35a9-74e0-55ec-b149-d360ff49b807"
+#IntervalRootFinding = "d2bf35a9-74e0-55ec-b149-d360ff49b807"
 JSON = "682c06a0-de6a-54ab-a142-c8b1cf79cde6"
 Polynomials = "f27b6e38-b328-58d1-80ce-0feddd5e7a45"
 SpecialFunctions = "276daf66-3868-5448-9aa4-cd146d93841b"
@@ -49,4 +48,4 @@ Unitful = "1986cc42-f94f-5a68-af5c-568840ba703d"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
 
 [targets]
-test = ["Aqua", "ChainRulesTestUtils", "JSON", "SpecialFunctions", "Statistics", "Test", "BenchmarkTools", "ForwardDiff", "Polynomials", "Unitful", "Zygote", "IntervalRootFinding"]
+test = ["Aqua", "ChainRulesTestUtils", "JSON", "SpecialFunctions", "Statistics", "Test", "BenchmarkTools", "ForwardDiff", "Polynomials", "Unitful", "Zygote"] #, "IntervalRootFinding"]

src/Bracketing/bisection.jl

@@ -44,7 +44,6 @@ function init_state(
     if x₀ > x₁
         x₀, x₁, fx₀, fx₁ = x₁, x₀, fx₁, fx₀
     end
-
     # handle interval if fa*fb ≥ 0 (explicit, but also not needed)
     (iszero(fx₀) || iszero(fx₁)) &&
         return UnivariateZeroState(promote(x₁, x₀)..., promote(fx₁, fx₀)...)
@@ -57,7 +56,6 @@ function init_state(
 
     # handles case where a=-0.0, b=1.0 without error
     sign(a) * sign(b) < 0 && throw(ArgumentError("_middle error"))
-
     UnivariateZeroState(promote(b, a)..., promote(fb, fa)...)
 end
 
@@ -180,10 +178,10 @@ function solve!(
     val, stopped = :not_converged, false
     ctr = 1
     log_step(l, M, state; init=true)
-
+    T,S = TS(state)
     while !stopped
-        a, b = state.xn0, state.xn1
-        fa, fb = state.fxn0, state.fxn1
+        a::T,  b::T  = state.xn0,  state.xn1
+        fa::S, fb::S = state.fxn0, state.fxn1
 
         ## assess_convergence
         if nextfloat(a) ≥ b

src/state.jl

@@ -6,6 +6,8 @@ struct UnivariateZeroState{T,S} <: AbstractUnivariateZeroState{T,S}
     fxn0::S
 end
 
+TS(::AbstractUnivariateZeroState{T,S}) where {T,S} = T,S
+
 # simple helper to set main properties of a state object
 function _set(state, xf1)
     x, fx = xf1

test/test_extensions.jl

@@ -20,20 +20,20 @@ end
 
 using ForwardDiff
 @testset "ForwardDiff" begin
-    f(x, p) = x^2 - p
+    f = (x, p) -> x^2 - p
     Z  = ZeroProblem(f, (0, 1000))
-    F(p) = solve(Z, Roots.Bisection(), p)
+    F = p -> solve(Z, Roots.Bisection(), p)
     for p ∈ (3,5,7,11)
         @test F(p) ≈ sqrt(p)
         @test ForwardDiff.derivative(F, p) ≈ 1 / (2sqrt(p))
     end
 
     # Hessian is *broken*
-    f(x, p) = x^2 - sum(p.^2)
+    f = (x, p) -> x^2 - sum(p.^2)
     Z = ZeroProblem(f, (0, 1000))
-    F(p) = solve(Z, Roots.Bisection(), p)
+    F = p -> solve(Z, Roots.Bisection(), p)
     Z = ZeroProblem(f, (0, 1000))
-    F(p) = solve(Z, Roots.Bisection(), p)
+    F = p  -> solve(Z, Roots.Bisection(), p)
     hess(f, p) = ForwardDiff.jacobian(p -> ForwardDiff.gradient(F, p), p)
     for p ∈ ([1,2], [1,3], [1,4])
         @test F(p) ≈ sqrt(sum(p.^2))
@@ -42,9 +42,9 @@ using ForwardDiff
         n = sqrt(a^2 + b^2)^3
         @test hess(F, p) ≈ [b^2 -a*b; -a*b a^2]/n
     end
-
 end
 
+#=
 using IntervalRootFinding
 @testset "IntervalRootFinding" begin
     f(x) = sin(x + sin(x + sin(x)))
@@ -53,3 +53,4 @@ using IntervalRootFinding
     @test sort(out.zeros) ≈ sort([-pi,0,pi])
     @test isempty(out.unknown)
 end
+=#

test/test_find_zero.jl

@@ -118,6 +118,14 @@ struct Order3_Test <: Roots.AbstractSecantMethod end
         @test @inferred(find_zero(sin, SomeInterval(3, 4))) ≈ pi
         @test @inferred(find_zero(sin, range(3, stop=4, length=20))) ≈ pi
     end
+
+    # test issue when non type stalbe
+    h(x) = x < 2000 ? -1000 : -1000 + 0.1 * (x - 2000)
+    a, b, xᵅ = 0, 20_000, 12_000
+    for M ∈ bracketing_meths
+        @test find_zero(h, (a,b), M) ≈ xᵅ
+    end
+
 end
 
 @testset "non simple zeros" begin