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Loop over diagind in diag for banded matrices #1211

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Merged
merged 1 commit into from
Feb 19, 2025
+14 −10
Merged

Loop over diagind in diag for banded matrices #1211

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7 changes: 4 additions & 3 deletions src/bidiag.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -405,14 +405,15 @@ end
function diag(M::Bidiagonal, n::Integer=0)
# every branch call similar(..., ::Int) to make sure the
# same vector type is returned independent of n
v = similar(M.dv, max(0, length(M.dv)-abs(n)))
dinds = diagind(M, n, IndexStyle(M))
v = similar(M.dv, length(dinds))
if n == 0
copyto!(v, M.dv)
elseif (n == 1 && M.uplo == 'U') || (n == -1 && M.uplo == 'L')
copyto!(v, M.ev)
elseif -size(M,1) <= n <= size(M,1)
for i in eachindex(v)
v[i] = M[BandIndex(n,i)]
for i in eachindex(v, dinds)
@inbounds v[i] = M[BandIndex(n,i)]
end
end
return v
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7 changes: 4 additions & 3 deletions src/diagonal.jl
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Expand Up @@ -836,12 +836,13 @@ permutedims(D::Diagonal, perm) = (Base.checkdims_perm(axes(D), axes(D), perm); D
function diag(D::Diagonal, k::Integer=0)
# every branch call similar(..., ::Int) to make sure the
# same vector type is returned independent of k
v = similar(D.diag, max(0, length(D.diag)-abs(k)))
dinds = diagind(D, k, IndexStyle(D))
v = similar(D.diag, length(dinds))
if k == 0
copyto!(v, D.diag)
else
for i in eachindex(v)
v[i] = D[BandIndex(k, i)]
for i in eachindex(v, dinds)
@inbounds v[i] = D[dinds[i]]
end
end
return v
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10 changes: 6 additions & 4 deletions src/tridiag.jl
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Expand Up @@ -191,15 +191,16 @@ _eviter_transposed(M::SymTridiagonal) = (transpose(x) for x in _evview(M))
function diag(M::SymTridiagonal, n::Integer=0)
# every branch call similar(..., ::Int) to make sure the
# same vector type is returned independent of n
v = similar(M.dv, max(0, length(M.dv)-abs(n)))
dinds = diagind(M, n, IndexStyle(M))
v = similar(M.dv, length(dinds))
if n == 0
return copyto!(v, _diagiter(M))
elseif n == 1
return copyto!(v, _evview(M))
elseif n == -1
return copyto!(v, _eviter_transposed(M))
else
for i in eachindex(v)
for i in eachindex(v, dinds)
v[i] = M[BandIndex(n,i)]
end
end
Expand Down Expand Up @@ -662,15 +663,16 @@ issymmetric(S::Tridiagonal) = all(issymmetric, S.d) && all(Iterators.map((x, y)
function diag(M::Tridiagonal, n::Integer=0)
# every branch call similar(..., ::Int) to make sure the
# same vector type is returned independent of n
v = similar(M.d, max(0, length(M.d)-abs(n)))
dinds = diagind(M, n, IndexStyle(M))
v = similar(M.d, length(dinds))
if n == 0
copyto!(v, M.d)
elseif n == -1
copyto!(v, M.dl)
elseif n == 1
copyto!(v, M.du)
elseif abs(n) <= size(M,1)
for i in eachindex(v)
for i in eachindex(v, dinds)
v[i] = M[BandIndex(n,i)]
end
end
Expand Down