PhpSpreadsheet/tests/data/Calculation/Financial/EFFECT.php

<?php

// nominal_rate, npery, Result

return [
    [
        0.052499999999999998,
        4,
        0.053542667370758003,
    ],
    [
        0.10000000000000001,
        4,
        0.103812890625,
    ],
    [
        0.10000000000000001,
        2,
        0.10249999999999999,
    ],
    [
        0.025000000000000001,
        2,
        0.025156250000000002,
    ],
    [
        1,
        0,
        '#NUM!',
    ],
];