/// <summary>
/// Calculates the inverse of a 4x4 matrix.
/// </summary>
/// <param name="m">The matrix to invert.</param>
/// <returns>A new <see cref="mat4"/> matrix that is the inverse of the input. Returns the identity matrix if the determinant is near zero.</returns>
// m5stackfp enclosure — AtomS3R + Unit Fingerprint2 in one slab.
//
// A FRAME, not a box. The short ends are OPEN: no bar of plastic across them,
// only the rim turning the corner. So the AtomS3R's USB-C plugs straight in
// with nothing above it, and at the far end the sensor's Grove cable leaves
IMPORTANT: Do not use it for transactions LARGER THAN $15,000!!! If you exceed that amount, they will ask for your ID and hold your swap until your identity is verified - and we dont want that. Personally I have been doing multiple $15,000 swaps so far, and worked just fine (none of them triggered KYC/AML checks).