ABSTRACT
In an orthonormal basis, a linear operator  is represented by the matrix () A ˆ = ( 2 λ 1+ λ 1+ λ λ ) , https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429092053/5e12ab0e-ba42-4caa-9bdf-6325e9117d3e/content/eqn18_1.tif"/>
