polynomialRoot - Incorrect roots returned for small coefficients

[Kat Fairbanks]

Describe the bug

When the coefficients are small (~1e-5, with epsilon set to the default 1e-12), polynomialRoot will return the wrong roots for cubic polynomials.

To Reproduce

Take the example function (x - 1)(x - 2)(x - 3), and then multiply it by different powers of 10. This should always return the same roots, but it starts returning different results when multiplying by 1e-5 or smaller.

const baseCoeff = [-6, 11, -6, 1];

math.polynomialRoot(...baseCoeff);
// => [ 1, 3, 2 ]

math.polynomialRoot(...baseCoeff.map((c) => 1e-4 * c));
// => [ 0.9999999999999983, 2.9999999999999973, 2.0000000000000036 ]

math.polynomialRoot(...baseCoeff.map((c) => 1e-5 * c));
// => [ 2.0000000000000235, 1.9999999999999987 ]

[Jos de Jong]

Thanks for your inputs @katzenbar.

These results are correct but they contain regular floating point round-off errors.

See docs: https://mathjs.org/docs/datatypes/numbers.html#roundoff-errors