Flaky: NativeLinAlg.dot matrix-matrix ComplexDouble returns wrong result on Linux

[devcrocod]

Multik version

0.3.0

Module

multik-openblas

Platform

JVM

Operating System

Linux

Description

NativeLinAlg.dot for matrix-matrix multiplication with ComplexDouble produces incorrect results intermittently on Linux (Ubuntu 22.04.5 LTS, gcc-12 12.3.0, JDK 21 Temurin). The test uses small integer ComplexDouble matrices with exact expected values and assertEquals — no tolerance. Failed in 3 out of 4 CI runs, making it the most frequently failing test.

Reproducer

val matrix1 = mk.ndarray(
    mk[mk[ComplexDouble(1, 2), ComplexDouble(3, 4)],
        mk[ComplexDouble(2, 3), ComplexDouble(4, 5)],
        mk[ComplexDouble(3, 4), ComplexDouble(5, 6)]]
)
val matrix2 = mk.ndarray(
    mk[mk[ComplexDouble(9, 8), ComplexDouble(7, 6), ComplexDouble(5, 4)],
        mk[ComplexDouble(8, 7), ComplexDouble(6, 5), ComplexDouble(4, 3)]]
)

val actual = NativeLinAlg.dot(matrix1, matrix2)
assertEquals(expected, actual) // Fails intermittently

Additional information

Flaky — failed in 3/4 CI runs.
All failures are AssertionFailedError at NativeLinAlgTest.kt:134.
CI runs: 22511673326, 22511741037, 22511767151.
Environment: Ubuntu 22.04.5 LTS, gcc-12 (12.3.0), g++-12, JDK 21 Temurin, x86_64.