assert bracket; close issue #414 (#415)

Author: jverzani

Project.toml

@@ -1,6 +1,6 @@
 name = "Roots"
 uuid = "f2b01f46-fcfa-551c-844a-d8ac1e96c665"
-version = "2.1.0"
+version = "2.1.1"
 
 [deps]
 ChainRulesCore = "d360d2e6-b24c-11e9-a2a3-2a2ae2dbcce4"

src/Bracketing/alefeld_potra_shi.jl

@@ -56,6 +56,8 @@ function init_state(::AbstractAlefeldPotraShi, F, x₀, x₁, fx₀, fx₁; c=no
         promote(b, a, a, a)...,
         promote(fb, fa, fa, fa)...,
     )
+    assert_bracket(fa, fb)
+
 
     if a > b
         a, b, fa, fb = b, a, fb, fa

test/test_bracketing.jl

@@ -308,6 +308,12 @@ end
     @test maxfailures <= 0
     @test maxresidual <= 1e-5
     @test avg(cnts) <= 3000
+
+    ## issue 412 check for bracket
+    f = x -> x - 1
+    for M ∈ Ms
+        @test_throws ArgumentError find_zero(f, (-3,0), M)
+    end
 end
 
 ## Some tests for FalsePosition methods