Flaky: QR decomposition ComplexDouble returns wrong result on Linux

[devcrocod]

Multik version

0.3.0

Module

multik-openblas

Platform

JVM

Operating System

Linux

Description

NativeLinAlgEx.qrC for ComplexDouble matrices produces incorrect QR decomposition intermittently on Linux (Ubuntu 22.04.5 LTS, gcc-12 12.3.0, JDK 21 Temurin). The test generates a 4x3 random ComplexDouble matrix (seeded with Random(42)), decomposes it into Q and R, and verifies Q*R = A with epsilon 1e-6. Failed in 2 out of 4 CI runs.

Reproducer

val a = data.getComplexDoubleM(4, 3) // deterministic 4x3 ComplexDouble matrix from Random(42)
val (q, r) = NativeLinAlgEx.qrC(a)

assertComplexFloatingNDArray(a, NativeLinAlgEx.dotMMComplex(q, r), epsilon = 1e-6) // Fails intermittently

Additional information

Flaky — failed in 2/4 CI runs.
AssertionFailedError at NativeLinAlgTest.kt:382.
CI runs: 22511673326, 22511741037.
Environment: Ubuntu 22.04.5 LTS, gcc-12 (12.3.0), g++-12, JDK 21 Temurin, x86_64.