Error with tolerance in test.

[julianmateu]

Error with tolerance in test.

[basicNew]

Couple of thoughts:

1. The 2.7755575615628914E-17 vs 0.0 looks like an expected rounding error. Comparing floats is a hard thing, as IEEE floating point arithmetic can't represent the whole Real space (see e.g. https://docs.python.org/2/tutorial/floatingpoint.html). To cope with this testing frameworks have a way to assert equality in a given delta (see e.g. http://stackoverflow.com/questions/7554281/junit-assertions-make-the-assertion-between-floats)
2. The 1.0714285714285714 vs 1.0 does seem suspicious. Are you sure there is no coding error?
3. getters and setters are also good to isolate your class implementation from itself, so you could change this.r for this.getR()

[julianmateu]

assertEquals(new Quaternion(1, 2, 3, 4).multiply(new Quaternion(
                        ((double)1.0)/28, ((double)-2.0)/28, ((double)-3.0)/28, ((double)-4.0)/28)),
                new Quaternion(1, 0, 0, 0)); // Multiplying by right inverse.

The problem with the 1.0714285714285714 vs 1.0 was because the norm of the quaternion was 30, not 28.

The 2.7755575615628914E-17 vs 0.0 was a rounding error problem, so I created a new assert with a tolerance, comparing each component of the two quaternions with an assertEquals.

[basicNew]

👍