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Make duals' operations through steprange use linrange instead #618

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Make duals' operations through steprange use linrange instead #618

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2c3a91c
Make duals' operations through steprange use linrange instead
tom-plaa Dec 14, 2022
a321237
Update test/DualTest.jl
tom-plaa Dec 14, 2022
3319d5e
Remove construction using Duals and (:) operator
tom-plaa Jan 3, 2023
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10 changes: 10 additions & 0 deletions src/dual.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -775,6 +775,16 @@ function LinearAlgebra.eigen(A::SymTridiagonal{<:Dual{Tg,T,N}}) where {Tg,T<:Rea
Eigen(λ,Dual{Tg}.(Q, tuple.(parts...)))
end

# StepRange - default to operate with LinRange to avoid TwicePrecision #
#----------------------------------------------------------------------#

Base.:*(x::Dual, r::StepRangeLen{<:Real,<:Base.TwicePrecision}) =
LinRange(x * first(r), x * last(r), length(r))

Base.:/(r::StepRangeLen{<:Real,<:Base.TwicePrecision}, x::Dual) =
LinRange(first(r) / x, last(r) / x, length(r))


# Functions in SpecialFunctions which return tuples #
# Their derivatives are not defined in DiffRules #
#---------------------------------------------------#
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55 changes: 55 additions & 0 deletions test/DualTest.jl
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Expand Up @@ -659,4 +659,59 @@ end
@test ForwardDiff.derivative(float, 1)::Float64 === 1.0
end

function deriv_check(f, x::Real; kw...)
fdual = f(ForwardDiff.Dual(x,1))
ty = fdual isa AbstractRange || !(f(x) isa AbstractRange)
t0 = isapprox(f(x), ForwardDiff.value.(fdual); kw...)
t1 = isapprox(ForwardDiff.derivative(f, x),
Calculus.derivative(f, x); kw...)
t1i = isapprox(ForwardDiff.derivative(x -> f(x)[1+end÷2], x),
Calculus.derivative(x -> f(x)[1+end÷2], x); kw...)
ty && t0 && t1 && t1i
end

@testset "ranges + Calculus" begin
# op(Dual, StepRangeLen) was broken, issue #380
@test (0:0.1:1) isa StepRangeLen

@test deriv_check(x -> (0:0.1:1) * x, 1.0)
@test deriv_check(x -> (0:0.1:1) .* x, 1.0)
@test deriv_check(x -> x * (0:0.1:1), 1.0)
@test deriv_check(x -> x .* (0:0.1:1), 1.0)

@test deriv_check(x -> (0:0.1:1) / x, 1.0) # makes a LinRange, after PR#618
@test deriv_check(x -> (0:0.1:1) ./ x, 1.0) # different path, at present a StepRangeLen

@test deriv_check(x -> (0:0.1:1) .+ x, 1.0)
@test deriv_check(x -> x .+ (0:0.1:1), 1.0)
@test deriv_check(x -> (0:0.1:1) .- x, 1.0)
@test deriv_check(x -> x .- (0:0.1:1), 1.0)

# op(Dual, StepRange) was never a problem
@test (2:3:11) isa StepRange

@test deriv_check(x -> (2:3:11) * x, 1.0)
@test deriv_check(x -> (2:3:11) / x, 1.0)
@test deriv_check(x -> (2:3:11) .+ x, 1.0)

# op(Dual, LinRange) was never a problem
@test deriv_check(x -> LinRange(1,2,3) * x, 1.0)
@test deriv_check(x -> LinRange(1,2,3) / x, 1.0)
@test deriv_check(x -> LinRange(1,2,3) .+ x, 1.0)

# Construction
@test deriv_check(x -> range(x, 3, length=5), 1.0)
@test deriv_check(x -> range(x, 3x, length=5), 1.0)
@test deriv_check(x -> range(x, step=2, length=5), 1.0)
@test deriv_check(x -> range(x, step=2x, length=5), 1.0)
@test deriv_check(x -> range(1, step=x, length=5), 1.0)

@test deriv_check(x -> x:2:6, 1.0) # perturbing x does not change the length
@test deriv_check(x -> 0.5:x:5, 1.0)
@test deriv_check(x -> 1:x:6, 2) # perturbing x does not change the length
@test deriv_check(x -> 1:2:x, 6) # perturbing x has no effect
@test deriv_check(x -> 1:2:x, 6.0) # perturbing x has no effect
end


end # module