JuliaArrays / JuliaArrays/InfiniteArrays.jl
Extend `exp(A::AbstractMatrix)`
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- Julia
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Description
The method exp(A::AbstractMatrix) is too limited and doesn't support most of the lazy types:
julia> using InfiniteArrays
julia> a = cache(Ones(∞, ∞)); a[1, 1] = 0; b = view(a, 1:5, 1:5);
julia> typeof(b)
SubArray{Float64, 2, LazyArrays.CachedArray{Float64, 2, Matrix{Float64}, Ones{Float64, 2, Tuple{InfiniteArrays.OneToInf{Int64}, InfiniteArrays.OneToInf{Int64}}}}, Tuple{UnitRange{Int64}, UnitRange{Int64}}, false}
julia> exp(b)
ERROR: MethodError: no method matching exp(::SubArray{Float64, 2, LazyArrays.CachedArray{Float64, 2, Matrix{Float64}, Ones{Float64, 2, Tuple{InfiniteArrays.OneToInf{Int64}, InfiniteArrays.OneToInf{Int64}}}}, Tuple{UnitRange{Int64}, UnitRange{Int64}}, false})
Closest candidates are:
exp(::Union{Float16, Float32, Float64}) at /usr/share/julia/base/special/exp.jl:296
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Float32, Float64, ComplexF32, ComplexF64}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:560
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Integer, Complex{<:Integer}}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:561
...
Stacktrace:
[1] top-level scope
@ REPL[4]:1
or
julia> exp(.√(Diagonal(0:∞)[:, 2:end]))
ERROR: MethodError: no method matching exp(::LazyArrays.BroadcastMatrix{Float64, typeof(sqrt), Tuple{SubArray{Int64, 2, Diagonal{Int64, InfiniteArrays.InfUnitRange{Int64}}, Tuple{Base.Slice{InfiniteArrays.OneToInf{Int64}}, InfiniteArrays.InfUnitRange{Int64}}, false}}})
Closest candidates are:
exp(::Union{Float16, Float32, Float64}) at /usr/share/julia/base/special/exp.jl:296
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Float32, Float64, ComplexF32, ComplexF64}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:560
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Integer, Complex{<:Integer}}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:561
...
Stacktrace:
[1] top-level scope
@ REPL[19]:1
julia> exp(5exp(3im) * (.√(Diagonal(0:∞)[:, 2:end]))^2)
ERROR: MethodError: no method matching exp(::LazyArrays.ApplyArray{ComplexF64, 2, typeof(*), Tuple{LazyArrays.BroadcastMatrix{ComplexF64, typeof(*), Tuple{ComplexF64, LazyArrays.BroadcastMatrix{Float64, typeof(sqrt), Tuple{SubArray{Int64, 2, Diagonal{Int64, InfiniteArrays.InfUnitRange{Int64}}, Tuple{Base.Slice{InfiniteArrays.OneToInf{Int64}}, InfiniteArrays.InfUnitRange{Int64}}, false}}}}}, LazyArrays.BroadcastMatrix{Float64, typeof(sqrt), Tuple{SubArray{Int64, 2, Diagonal{Int64, InfiniteArrays.InfUnitRange{Int64}}, Tuple{Base.Slice{InfiniteArrays.OneToInf{Int64}}, InfiniteArrays.InfUnitRange{Int64}}, false}}}}})
Closest candidates are:
exp(::Union{Float16, Float32, Float64}) at /usr/share/julia/base/special/exp.jl:296
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Float32, Float64, ComplexF32, ComplexF64}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:560
exp(::StridedMatrix{var"#s859"} where var"#s859"<:Union{Integer, Complex{<:Integer}}) at /usr/share/julia/stdlib/v1.7/LinearAlgebra/src/dense.jl:561
...
Stacktrace:
[1] top-level scope
@ REPL[23]:1
Contributor guide
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start by locating the implementation of exp(::AbstractMatrix) and any existing tests for matrix exponentials. Reproduce the SubArray and lazy-array examples in the issue to identify the unsupported dispatch cases. Done means exp works for the demonstrated lazy matrix types without the reported MethodErrors.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- julia
- Domain
- data
- Issue type
- Feature
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100