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Use pivoting as the default in LU regardless of the element type. #32989

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Merged
merged 1 commit into from
Aug 23, 2019
Merged

Use pivoting as the default in LU regardless of the element type. #32989

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27 changes: 2 additions & 25 deletions stdlib/LinearAlgebra/src/lu.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -179,13 +179,6 @@ function generic_lufact!(A::StridedMatrix{T}, ::Val{Pivot} = Val(true);
return LU{T,typeof(A)}(A, ipiv, convert(BlasInt, info))
end

# floating point types doesn't have to be promoted for LU, but should default to pivoting
function lu(A::Union{AbstractMatrix{T}, AbstractMatrix{Complex{T}}},
pivot::Union{Val{false}, Val{true}} = Val(true);
check::Bool = true) where {T<:AbstractFloat}
lu!(copy(A), pivot; check = check)
end

function lutype(T::Type)
# In generic_lufact!, the elements of the lower part of the matrix are
# obtained using the division of two matrix elements. Hence their type can
Expand Down Expand Up @@ -274,26 +267,10 @@ julia> l == F.L && u == F.U && p == F.p
true
```
"""
function lu(A::AbstractMatrix{T}, pivot::Union{Val{false}, Val{true}};
function lu(A::AbstractMatrix{T}, pivot::Union{Val{false}, Val{true}}=Val(true);
check::Bool = true) where T
S = lutype(T)
AA = similar(A, S)
copyto!(AA, A)
lu!(AA, pivot; check = check)
end
# We can't assume an ordered field so we first try without pivoting
function lu(A::AbstractMatrix{T}; check::Bool = true) where T
S = lutype(T)
AA = similar(A, S)
copyto!(AA, A)
F = lu!(AA, Val(false); check = false)
if issuccess(F)
return F
else
AA = similar(A, S)
copyto!(AA, A)
return lu!(AA, Val(true); check = check)
end
lu!(copy_oftype(A, S), pivot; check = check)
end

lu(S::LU) = S
Expand Down
15 changes: 12 additions & 3 deletions stdlib/LinearAlgebra/test/lu.jl
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Expand Up @@ -301,10 +301,19 @@ include("trickyarithmetic.jl")
@testset "lu with type whose sum is another type" begin
A = TrickyArithmetic.A[1 2; 3 4]
ElT = TrickyArithmetic.D{TrickyArithmetic.C,TrickyArithmetic.C}
B = lu(A)
B = lu(A, Val(false))
@test B isa LinearAlgebra.LU{ElT,Matrix{ElT}}
C = lu(A, Val(false))
@test C isa LinearAlgebra.LU{ElT,Matrix{ElT}}
end

@testset "Issue #30917. Determinant of integer matrix" begin
@test det([1 1 0 0 1 0 0 0
1 0 1 0 0 1 0 0
1 0 0 1 0 0 1 0
0 1 1 1 0 0 0 0
0 1 0 0 0 0 1 1
0 0 1 0 1 0 0 1
0 0 0 1 1 1 0 0
0 0 0 0 1 1 0 1]) ≈ 6
end

end # module TestLU