Floating point error in Matrix.invert()

[hal7df]

Both of the (valid) unit tests for Matrix.invert() require an epsilon scale factor of 1e10 (i.e. only accurate to 5-6 decimal places), which is undesirable. This should be investigated to find a solution for increasing the accuracy of the inversion operation.

Curiously, the rref() method seems to be accurate to 14 decimal places, yet the inverse it produces is less accurate. Is this a side effect of the algorithm/is there a better matrix inversion algorithm to use?

Here's an example from one of the test cases:

Actual:

Computed:

Observed in Chromium 60.0.3112.78 on Ubuntu 16.04