Givens matrix for an integer vector

Specific Domains Numerics
1

As a newcomer to Julia I am still struggling with various type-related issues. One of them is this:

using LinearAlgebra
julia> x = [3,4]
2-element Array{Int64,1}:
 3
 4

julia> G,r = givens(x,1,2)
ERROR: MethodError: no method matching givensAlgorithm(::Int64, ::Int64)
Stacktrace:
 [1] givens(::Int64, ::Int64, ::Int64, ::Int64) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.1/LinearAlgebra/src/givens.jl:276
 [2] givens(::Array{Int64,1}, ::Int64, ::Int64) at /buildworker/worker/package_linux64/build/usr/share/julia/stdlib/v1.1/LinearAlgebra/src/givens.jl:317
 [3] top-level scope at none:0

If instead I define x as a vector containing floats, things are fine:

julia> x = [3.0,4.0]
2-element Array{Float64,1}:
 3.0
 4.0

julia> G,r = givens(x,1,2)
(LinearAlgebra.Givens{Float64}(1, 2, 0.6, 0.8), 5.0)

Is this really an anticipated behavior? In the documentation I can read that givens can be called as givens(x::AbstractVector, i1::Integer, i2::Integer). Shouldn’t then a vector of integers be perfectly fine?

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2

This looks like a bug, I’d file an issue

3 Likes
3

Interestingly, there is a method

givensAlgorithm(f, g) = givensAlgorithm(promote(float(f), float(g))...)

As @dlfivefifty said, this looks like a bug and should work.

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4

Notice that this method was added very recently so it’s not available in the latest release of Julia.

1 Like
5

Thanks for the opinion. I have filed a bug: https://github.com/JuliaLang/julia/issues/32388.

6

Andreas, you closed the issue on github https://github.com/JuliaLang/julia/issues/32388 while explaining that the problem had already been fixed. Could you, however, give me a hint on how to proceed now, before the fix reaches the release of Julia? For example, will my switching to some nightly build help? Thanks.

7

Yes. You could either use nightly but it is probably simpler just to carry the definition locally until the next version of Julia is released since it is so small.

2 Likes