Optics measurement in the LHC close to the half integer tune resonance

Two methods for deriving the Beta-functions were studied, as a discrepancy occured when approaching the half integer resonance. Several simulations have been performed to study the behaviour of the two methods under different controlled circumstances. An ideal accelerator without any errors of the magnetic components was simulated before magnetic field errors were added to the simulation. A new algorithm was devoloped in order to improve the computation of the Beta-functions.