feynlag.vacuum.diagonalize.rotation_2x2¶ feynlag.vacuum.diagonalize.rotation_2x2(theta)[source]¶ R(θ) = [[cosθ, sinθ], [−sinθ, cosθ]] — new₁ = cθ old₁ + sθ old₂, new₂ = −sθ old₁ + cθ old₂.