JuliaArrays / JuliaArrays/StaticArrays.jl
result of A\b is different with StaticArrays
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Description
While running my program I have found x=A\b sometimes gives a different result when using StaticArrays. A is a 3x3 Matrix and b is a 3x1 Matrix.
A = [3.1916757882237305e11 7.90810107400456e10 798958.7959618106; 7.90810107400456e10 1.959448361045036e10 197960.17301454322; 798958.7959618106 197960.17301454322 2.0]
b = [-390.11659959072784; -96.66024072975743; -0.0009765625]
Solving A\b with default Matrices I get:
x =[1.2650904540083241e-20; -3.9907885656377556e-31; -0.0004882812500050538]
err = norm(A*x -b) gives 0
Solving A\b with StaticArrays I get:
x = [-1.222243483259749e-9; -3.79355666251685e-9; -0.0004100774669296476]
err = norm(A*x-b) gives 646.5957086789485
I suspect the version with default Matrices is the correct result, and there is something missing in A\b with StaticArrays.
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Research direction
Start by reproducing the reported A\b results with the provided 3x3 A and b values using regular matrices and StaticArrays. Then inspect the StaticArrays solve path and relevant tests; done means the two approaches produce a numerically valid result with a residual consistent with the reference.
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Assessment
- Tech stack
- julia
- Domain
- performance
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 35/100