Order 15 Hankel-Norm IIR Fit to Length 561 FIR Measured Trumpet-Bell Reflectance

• Order 15 is a ``sweet spot'' in the eigenvalues plot
• Hankel Norm is the only phase-sensitive IIR error norm we know which can always be reliably minimized in principle
• Norm is sensitive to linear magnitude error, not dB
• This bell filter is too ``bright'' and fit is generally poor
• Initial time-domain match is reasonable, but it can't ``hold on'' until the main reflection
• Numerical failure is a likely (in Matlab/PentiumII doubles)