Linear Algebra, Svd, Eigenvectors, Eigenvalue, Data Science.
take, UᵀU = I (Identical). UUᵀ =I (Identical) ~Uᵀ~U = I (Identical). UUᵀ != I (Not identical) Not going deep into the properties like unitary transformations, covariance, pseudo-inverse matrixes, linear system of equations, etc in this article. If any of you is interested would write the next