Strange test failures on Julia 1.4, possibly related to ForwardDiff.jl

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1

Hi all

ARCHModels.jl (registered package) has test failures on Julia 1.4, see here. Tests pass on 1.3 and on nightly.

The really strange thing is that I can reproduce this locally, but only within Pkg.test; when I run the offending test in the REPL, it works fine (fresh Julia installation with no other packages installed).

The error is a singular Hessian computed with ForwardDiff.jl, but it doesn’t seem to be merely a numerical problem: When I add @show statements and run from the REPL, I get H[1:r, 1:r] = [-1.2294260247147748 -2.1964515660007304; -2.1964515660007313 -5.541465030396839], which isn’t even close to singular (H is the Hessian). During testing, I get H[1:r, 1:r] = [0.0 0.0; 0.0 1.0739314068747037e-16].

I have no idea how to debug this further, because it happens only when testing. Any help would be greatly appreciated.

Cheers,
Simon

2

Pkg.test runs with checkbounds=yes so that can sometimes explain things like this. Does it error in the REPL if you start julia with that flag?

1 Like
3

Thank you Frederik! That does trigger the error from the REPL.

I still have no idea why it’s failing on 1.4 but not on 1.3 or nightly, but at least that gives me chance to debug it :slight_smile:

Thanks again!