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Specialize lmul!/rmul! for adjoint/transpose #1388

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Merged
merged 6 commits into from
Aug 21, 2025
Merged

Specialize lmul!/rmul! for adjoint/transpose #1388

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d367a85
Specialize lmul!/rmul! for adjoint/transpose
jishnub Jun 19, 2025
a359c7c
Add complex tests
jishnub Jun 19, 2025
a462e5a
Restrict to real/complex numbers
jishnub Jun 21, 2025
b951b92
Merge branch 'master' into jishnub/lrmul_adjtrans
dkarrasch Aug 21, 2025
c14d687
extend to non-commutative numbers and adjoints
dkarrasch Aug 21, 2025
6ffc9f7
remove comment
dkarrasch Aug 21, 2025
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4 changes: 4 additions & 0 deletions src/adjtrans.jl
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Expand Up @@ -513,6 +513,10 @@ function _dot_nonrecursive(u, v)
end
end

# we use (n A^T) = (A n)^T, which holds if the product of n and the elements of A is commutative
rmul!(X::AdjOrTrans{<:Union{Real,Complex}}, s::Union{Real,Complex}) = (lmul!(wrapperop(X)(s), parent(X)); X)
lmul!(s::Union{Real,Complex}, X::AdjOrTrans{<:Union{Real,Complex}}) = (rmul!(parent(X), wrapperop(X)(s)); X)

# Adjoint/Transpose-vector * vector
*(u::AdjointAbsVec{<:Number}, v::AbstractVector{<:Number}) = dot(u.parent, v)
*(u::TransposeAbsVec{T}, v::AbstractVector{T}) where {T<:Real} = dot(u.parent, v)
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28 changes: 28 additions & 0 deletions test/adjtrans.jl
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Expand Up @@ -12,6 +12,7 @@ isdefined(Main, :LinearAlgebraTestHelpers) || Base.include(Main, TESTHELPERS)

using Main.LinearAlgebraTestHelpers.OffsetArrays
using Main.LinearAlgebraTestHelpers.ImmutableArrays
using Main.LinearAlgebraTestHelpers.Quaternions

@testset "Adjoint and Transpose inner constructor basics" begin
intvec, intmat = [1, 2], [1 2; 3 4]
Expand Down Expand Up @@ -809,4 +810,31 @@ end
end
end

@testset "lmul!/rmul! by numbers" begin
@testset "$(eltype(A))" for A in (rand(4, 4), rand(ComplexF64,4,4),
fill([1 2; 3 4], 4, 4),
fill(Quaternion(1,2,3,4), 4, 4))
B = copy(A)
@testset for op in (transpose, adjoint)
A .= B
@test lmul!(2, op(A)) == 2 * op(B)
A .= B
@test rmul!(op(A), 2) == op(B) * 2
if eltype(A) <: Complex
A .= B
@test lmul!(-2im, op(A)) == -2im * op(B)
A .= B
@test rmul!(op(A), -2im) == op(B) * -2im
end
if eltype(A) <: Quaternion
A .= B
q = Quaternion(0,1,4,7)
@test lmul!(q, op(A)) == q * op(B)
A .= B
@test rmul!(op(A), q) == op(B) * q
end
end
end
end

end # module TestAdjointTranspose