Use approximate comparison in LinearAlgebra diagonal tests. #34361
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dkarrasch
approved these changes
Jan 13, 2020
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Test failures unrelated (LinearAlgebra/diagonal succeeded in both cases). |
28 tasks
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But why are they not giving the exact same results here? When you multiply with a diagonal matrix, there is just a single multiplication involved so how could the left and right hand side not match? Usually, we need to allow for approximate equality because we allow the terms to be added in any order or because of one of the multiplications uses fused muladd but neither should apply here. |
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Reducing one of the failures (it fails both with 32 and 64 bit complex numbers): using LinearAlgebra
using Test
function main(T=Float32)
D = Diagonal(randn(Complex{T}, 4, 4))
B = randn(Complex{T}, 4, 4)
T = LowerTriangular(B)
println("Triangular * Diagonal:")
display(T*D)
println()
println("Reference:")
display(Array(T) * Array(D))
println()
println("Difference:")
display(abs.((T * D) .- (Array(T) * Array(D))))
println()
@test T * D == Array(T) * Array(D)
end
isinteractive() || main() |
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Ah then it makes sense. Fused muladd can of course make a difference for complex numbers. |
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Fixes failure seen on Aarch64: