Use === and !== for comparisons with nothing (JuliaMath#243)

* Use `===` and `!==` for comparisons with `nothing`

* Fix two additional comparisons

src/find_zero.jl

@@ -185,7 +185,7 @@ Tracks(s::AbstractUnivariateZeroState{T,S}) where {T, S} = Tracks(T,S)
 Tracks(verbose, tracks, state) = (verbose && isa(tracks, NullTracks)) ? Tracks(state) : tracks
 
 function log_step(l::Tracks, M::Any, state, init=nothing)
-    if init != nothing
+    if init !== nothing
         x₀, fx₀ = state.xn0, state.fxn0
         push!(l.xs, x₀)
         push!(l.fs, fx₀)
@@ -194,7 +194,7 @@ function log_step(l::Tracks, M::Any, state, init=nothing)
     push!(l.xs, x₁)
     push!(l.fs, fx₁)
 
-    init == nothing && log_steps(l, 1)
+    init === nothing && log_steps(l, 1)
     nothing
 end
 
@@ -217,8 +217,7 @@ function show_tracks(io::IO, s::Tracks, M::AbstractUnivariateZeroMethod)
 end
 
 function show_trace(io::IO, method, N, state, tracks)
-
-    if state == nothing
+    if state === nothing
         print(io, "Algorithm has not been run")
         return nothing
     end
@@ -228,7 +227,7 @@ function show_trace(io::IO, method, N, state, tracks)
     println(io, "Results of univariate zero finding:\n")
     if converged
         println(io, "* Converged to: $(state.xn1)")
-        if N == nothing || isa(method, AbstractBracketing)
+        if N === nothing || method isa AbstractBracketing
             println(io, "* Algorithm: $(method)")
         else
             println(io, "* Algorithm: $(method), with possible bracketing with $N")
@@ -783,7 +782,7 @@ end
 # This should be deprecated
 function Base.iterate(P::ZeroProblemIterator, st=nothing)
     ## st = (val, (state, ctr, val))
-    if st == nothing
+    if st === nothing
         state = P.state
         ctr = 1
     else
@@ -902,7 +901,7 @@ julia> function order0(f, x)
            fx = ZeroProblem(f, x)
            p = init(fx, Roots.Secant())
            xᵢ,st = ϕ = iterate(p)
-           while ϕ != nothing
+           while ϕ !== nothing
                xᵢ, st = ϕ
                state, ctr = st
                fᵢ₋₁, fᵢ = state.fxn0, state.fxn1

src/simple.jl

@@ -45,8 +45,8 @@ function bisection(f, a::Number, b::Number; xatol=nothing, xrtol=nothing)
     T = eltype(x1)
 
 
-    atol = xatol == nothing ? zero(T) : abs(xatol)
-    rtol = xrtol == nothing ? zero(one(T)) : abs(xrtol)
+    atol = xatol === nothing ? zero(T) : abs(xatol)
+    rtol = xrtol === nothing ? zero(one(T)) : abs(xrtol)
     CT = iszero(atol) && iszero(rtol) ?  Val(:exact) : Val(:inexact)
 
     x1, x2 = float(x1), float(x2)
@@ -313,8 +313,8 @@ function newton(f, x0; xatol=nothing, xrtol=nothing, maxevals = 100)
 
     x = float(x0)
     T = typeof(x)
-    atol = xatol != nothing ? xatol : oneunit(T) * (eps(one(T)))^(4/5)
-    rtol = xrtol != nothing ? xrtol : eps(one(T))^(4/5)
+    atol = xatol !== nothing ? xatol : oneunit(T) * (eps(one(T)))^(4/5)
+    rtol = xrtol !== nothing ? xrtol : eps(one(T))^(4/5)
 
 
     xo = Inf

test/test_derivative_free_interactive.jl

@@ -319,7 +319,7 @@ function read_in(fname)
     E["residuals"] = Dict()
     for (k,v) in D["residuals"]
         for vi in v
-            vi[vi .== nothing] .= NaN
+            vi[vi .=== nothing] .= NaN
         end
         E["residuals"][k] = vvta1(v, Float64)
     end

test/test_find_zero.jl

@@ -182,7 +182,7 @@ end
     options = Roots.init_options(M, state, xatol=1/2)
     ZPI = init(M,G1,state,options)
     ϕ = iterate(ZPI)
-    while ϕ != nothing
+    while ϕ !== nothing
         val, st = ϕ
         state, ctr = st
         ϕ = iterate(ZPI, st)
@@ -490,7 +490,7 @@ end
         ZPI = init(ZeroProblem(F, x0), M; kwargs...)
         x = NaN * float(x0)
         ϕ = iterate(ZPI)
-        while ϕ != nothing
+        while ϕ !== nothing
             x, st = ϕ
             F.cnt.contents >= maxfnevals && return NaN*float(x0)
             ϕ = iterate(ZPI, st)