Matrix calculator
https://matrixcalc.org/enMatrix addition, multiplication, inversion, determinant and rank calculation, transposing, bringing to diagonal, triangular form, exponentiation, LU Decomposition, Singular Value Decomposition (SVD), solving of systems of linear equations with solution steps
Rotation matrix - Wikipedia
https://en.wikipedia.org/wiki/Rotation_matrixGiven a 3 × 3 rotation matrix R, a vector u parallel to the rotation axis must satisfy =, since the rotation of u around the rotation axis must result in u.The equation above may be solved for u which is unique up to a scalar factor unless R = I.. Further, the equation may be rewritten = =, which shows that u lies in the null space of R − I.