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### D.8.2 `harminv` output

The result returned by a call to

    library('harminv','hsolve')

with valid input (`harminv` input parameters) is a list of similar tuples of the form

    <(amplitude,frequency,decay,quality,error)...>

with all members being real valued except for the amplitudes, which are complex. Each tuple describes a function of the form

    f(t) = A * sin (frequency * t + P) * exp (-decay * t)

such that the summation of these functions approximates the original given signal (`harminv` input parameters). The real amplitude `A` and phase `P` are given by the modulus and argument of the complex amplitude returned in the result,

    A = library('complex','cabs') amplitude
    P = library('complex','carg') amplitude

in terms of the complex library functions (`complex`). The error values are measures of the goodness of fit, and the quality factors are defined as

    quality = (pi * |frequency| / decay)

It may be useful in some applications to ignore components with quality factors outside of a certain range.

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