Flaky: PLU decomposition ComplexDouble returns wrong result on Linux

[devcrocod]

Multik version

0.3.0

Module

multik-openblas

Platform

JVM

Operating System

Linux

Description

NativeLinAlgEx.pluC for ComplexDouble matrices produces incorrect PLU decomposition intermittently on Linux (Ubuntu 22.04.5 LTS, gcc-12 12.3.0, JDK 21 Temurin). The test generates a 4x4 random ComplexDouble matrix (seeded with Random(42)), decomposes it into P, L, U, and verifies P*L*U = A with epsilon 1e-8. Failed in 2 out of 4 CI runs.

Reproducer

val a = data.getComplexDoubleM(4) // deterministic 4x4 ComplexDouble matrix from Random(42)
val (p, l, u) = NativeLinAlgEx.pluC(a)

val lu = NativeLinAlgEx.dotMMComplex(l, u)
val plu = NativeLinAlgEx.dotMMComplex(p, lu)
assertComplexFloatingNDArray(a, plu, epsilon = 1e-8) // Fails intermittently

Additional information

Flaky — failed in 2/4 CI runs.
AssertionFailedError at NativeLinAlgTest.kt:415.
CI runs: 22511673326, 22511741037.
Environment: Ubuntu 22.04.5 LTS, gcc-12 (12.3.0), g++-12, JDK 21 Temurin, x86_64.