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Merged
lkdvos merged 1 commit into from
Oct 28, 2026
Merged

Keep small highest-weight CGCs in gaugefix! #66

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11 changes: 5 additions & 6 deletions src/clebschgordan.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -357,26 +357,25 @@ function cref!(
)
nr, nc = size(A)
i = j = 1
# rows with entries below `ɛ` are not used as pivots, but are kept: as only column operations
# are applied to all rows, the columns of `A` keep spanning the same space
@inbounds while i <= nr && j <= nc
(m, mj) = findabsmax(view(A, i, j:nc))
mj = mj + j - 1
if m <= ɛ
if ɛ > 0
A[i, j:nc] .= zero(eltype(A))
end
i += 1
else
@simd for k in i:nr
@simd for k in 1:nr
A[k, j], A[k, mj] = A[k, mj], A[k, j]
end
d = A[i, j]
@simd for k in i:nr
@simd for k in 1:nr
A[k, j] /= d
end
for k in 1:nc
if k != j
d = A[i, k]
@simd for l in i:nr
@simd for l in 1:nr
A[l, k] -= d * A[l, j]
end
end
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4 changes: 2 additions & 2 deletions test/clebschgordan.jl
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Expand Up @@ -6,9 +6,9 @@ using SUNRepresentations: annihilation
using SparseArrayKit: nonzero_values

# for SU(2), the CGCs are known exactly: compare with those of SU2Irrep, which has the opposite
# basis order, up to an overall sign
# basis order, up to an overall sign (the largest spins have highest-weight CGCs below `TOL_GAUGE`)
@testset "SU(2) CGCs for large spins" begin
for (n1, n2, n3) in ((40, 40, 20), (80, 80, 80), (80, 41, 61))
for (n1, n2, n3) in ((40, 40, 20), (80, 80, 80), (80, 41, 61), (200, 200, 200), (250, 120, 200))
s1, s2, s3 = SUNIrrep{2}(n1, 0), SUNIrrep{2}(n2, 0), SUNIrrep{2}(n3, 0)
C = Array(CGC(Float64, s1, s2, s3))
ref = fusiontensor(SU2Irrep(n1 // 2), SU2Irrep(n2 // 2), SU2Irrep(n3 // 2))
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