Stability spectral radius

The traditional statement in stability theory that all of the eigenvalues have negative real part becomes 5( A) < 0. The spectral radius of a matrix, denoted u A), is defined by... 

The stability of the method therefore depends solely on the spectral radius of the matrix X. Denoting rj = then we compute... 

If the central plane of the near-confocal FPI is imaged by a lens onto a circular aperture with sufficiently small radius b < (Ar ) / only the central interference order is transmitted to the detector while all other orders are stopped. Because of the large radial dispersion for small p one obtains a high spectral resolving power. With this arrangement not only spectral line profiles but also the instrumental bandwidth can be measured, when an incident monochromatic wave (from a stabilized single-mode laser) is used. The mirror separation d = r - is varied by the small amount e and the power... 

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