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WIP: Add DCT-I test plan to test real-to-real transforms #141

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WIP: Add DCT-I test plan to test real-to-real transforms #141

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40 changes: 40 additions & 0 deletions test/TestPlans.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -294,4 +294,44 @@ Base.:*(p::WrapperTestPlan, x::AbstractArray) = p.plan * x
AbstractFFTs.plan_inv(p::WrapperTestPlan) = WrapperTestPlan(AbstractFFTs.plan_inv(p.plan))
Base.inv(p::WrapperTestPlan) = WrapperTestPlan(inv(p.plan))

#####
# DCT tests, to test real-to-real plans.
# We implement DCT-I by using its equivalence to an
# fft applied to [x; reverse(x)[2:end-1]]
####
struct TestDCTIPlan{T,N,FFTPlan} <: Plan{T}
fftplan::FFTPlan
sz::NTuple{N,Int}
function TestPlan{T}(fftplan::FFTPlan, sz::NTuple{N,Int}) where {T,N,FFTPlan}
return new{T,N,FFTPlan}(fftplan, sz)
end
end

Base.size(p::TestDCTIPlan) = p.sz
Base.ndims(::TestDCTIPlan{T,N}) where {T,N} = N


_doublesize((n,)::Tuple{Int}, region) = (2n-2,)

function plan_dctI(x::AbstractArray{T}, region; kwargs...) where {T}
return TestDCTIPlan{T}(plan_fft(Array{complex(float(T))}(undef, _doublesize(size(x), region)),region; kwargs...), size(x))
end

Base.:*(p::TestDCTIPlan, x::AbstractArray) = mul!(similar(x, complex(float(eltype(x)))), p, x)
function LinearAlgebra.mul!(
y::AbstractArray{<:Real,N}, p::TestPlan, x::AbstractArray{<:Real,N}
) where {N}
size(y) == size(p) == size(x) || throw(DimensionMismatch())
ret = Array{complex(float(eltype(y)))}(undef, size(p.fftplan))
tmp = similar(ret)
if N == 1
tmp[1:length(x)] = x
tmp[length(x)+1:end-1] = x[end-1:-1:2]
mul!(ret, p.fftplan, tmp)
copyto!(y, view(ret, 1:length(y)))
else
error("not implemented")
end
end

end
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