test_forwarddiff.jl's POLAR_MATRICES check flakes at ~4%, and the operating point 320e756 chose to prevent it does not move
test/solver/test_forwarddiff.jl:88 asserts rel_err < 1e-3 on max|jac_fwd - jac_fd| / max|jac_fwd|. It failed on #285's CI in Julia 1.12 - ubuntu - x64 - with code coverage at 0.0400, with the other five matrix cells green on the same commit. #285's diff is entirely inside the NONLIN branch of gamma_loop! (src/solver.jl:913-1010, which returns before the LOOP branch at :1012) and this test builds a solver_type=LOOP solver, so no changed line is reachable from it.
This is the third time the check has been in the frame. 320e756 recorded "one Windows run crossed 1e-3 at 0.044 while a re-run passed", moved y_op[1:4] off zero (defl_rad = deg2rad(1.0)) and loosened the bound to 0.1 in the same commit. ae11d48 then pinned NeuralFoil table generation to one BLAS thread, tightened the bound back to 1e-3, and put y_op[1:4] back to zeros(4). 0.0400 is the same jump as 0.044.
Measured here (VSM at the test's operating point, 8 panels, tables regenerated on this box):
rel_err = 3.31e-6, repeatable to four significant figures — 300x inside the 1e-3 bound. CI's 0.0400 is 12000x that, so it is a discrete derivative jump, not tolerance drift.- Flat in freestream alpha: 3.23e-6 at 5.0 deg, 3.23e-6 at 6.0 deg, 3.31e-6 at 7.5 deg, 3.23e-6 at 10.0 deg.
- Flat in theta: 3.314e-6 at theta = 0, and the same 3.314e-6 at 1e-12, -1e-12, 1e-9, -1e-9, 1e-6 and -1e-6; 3.316e-6 at 0.25 deg, 3.273e-6 at 1.0 deg, 3.307e-6 at -1.0 deg. There is no knife edge in theta anywhere between 0 and 1 deg.
That last line is the point: theta_idxs=1:4 feeds twist, and linearize passes delta_angles=nothing, so 320e756's defl_rad never moved the operating point off a delta knot. Its green run came from the 0.1 bound it set in the same commit, which ae11d48 was right to tighten. Restoring that operating point would buy nothing — worth writing down before someone reaches for it again.
Where the knife edge actually is, still open. Two candidates measured at the operating point:
- Every panel's
delta is exactly 0.0, which is exactly a knot of the table's delta_range = -3:3:3 deg. Whichever delta strip's slopes the interpolant selects at an exact knot decides the alpha-direction slopes, and the worst entry is always a theta column (2 or 3).
- The tip panels solve to alpha 19.04 and 18.93 deg, outside the table's
alpha_range = -5:5:15 deg, so they are extrapolated.
Deciding between them needs the environment that produces the 4% jump; it does not reproduce here. A fix that would follow from (1) is shifting delta_range so 0 is interior to a cell (e.g. deg2rad.(-4.5:3:4.5), putting the operating point 1.5 deg from the nearest knot, 2600x the 1e-5 finite-difference step) rather than moving an input that does not reach delta. Not done here: it changes what the test covers and I cannot show it red before and green after.
test_forwarddiff.jl's POLAR_MATRICES check flakes at ~4%, and the operating point 320e756 chose to prevent it does not move
test/solver/test_forwarddiff.jl:88assertsrel_err < 1e-3onmax|jac_fwd - jac_fd| / max|jac_fwd|. It failed on #285's CI inJulia 1.12 - ubuntu - x64 - with code coverageat 0.0400, with the other five matrix cells green on the same commit. #285's diff is entirely inside theNONLINbranch ofgamma_loop!(src/solver.jl:913-1010, whichreturns before theLOOPbranch at:1012) and this test builds asolver_type=LOOPsolver, so no changed line is reachable from it.This is the third time the check has been in the frame. 320e756 recorded "one Windows run crossed 1e-3 at 0.044 while a re-run passed", moved
y_op[1:4]off zero (defl_rad = deg2rad(1.0)) and loosened the bound to 0.1 in the same commit. ae11d48 then pinned NeuralFoil table generation to one BLAS thread, tightened the bound back to 1e-3, and puty_op[1:4]back tozeros(4). 0.0400 is the same jump as 0.044.Measured here (VSM at the test's operating point, 8 panels, tables regenerated on this box):
rel_err = 3.31e-6, repeatable to four significant figures — 300x inside the 1e-3 bound. CI's 0.0400 is 12000x that, so it is a discrete derivative jump, not tolerance drift.That last line is the point:
theta_idxs=1:4feeds twist, andlinearizepassesdelta_angles=nothing, so 320e756'sdefl_radnever moved the operating point off a delta knot. Its green run came from the 0.1 bound it set in the same commit, which ae11d48 was right to tighten. Restoring that operating point would buy nothing — worth writing down before someone reaches for it again.Where the knife edge actually is, still open. Two candidates measured at the operating point:
deltais exactly 0.0, which is exactly a knot of the table'sdelta_range = -3:3:3deg. Whichever delta strip's slopes the interpolant selects at an exact knot decides the alpha-direction slopes, and the worst entry is always a theta column (2 or 3).alpha_range = -5:5:15deg, so they are extrapolated.Deciding between them needs the environment that produces the 4% jump; it does not reproduce here. A fix that would follow from (1) is shifting
delta_rangeso 0 is interior to a cell (e.g.deg2rad.(-4.5:3:4.5), putting the operating point 1.5 deg from the nearest knot, 2600x the 1e-5 finite-difference step) rather than moving an input that does not reach delta. Not done here: it changes what the test covers and I cannot show it red before and green after.