Quadratic Equation in estimateRyx

[JadBatmobile]

I am trying to understand the mathematics involved in the estimateRyx, specifically, in lines 518 - 552, where the two eigen vectors t1 and t2 are processed to yield R_yx.

I have read the source paper, which states that the constraints are used to solve for this quaternion, but they do not go into the mathematical details of it.

Thank you