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Re: cubic vs quintic spline

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  • Re: cubic vs quintic spline

    Jesus Dapena noted that collecting extra data does not help for Vaughn's
    example of dropping an object or for impacts. He is absolutely correct.

    The issue here is that all smoothing algorithms make some assumptions about
    the data, especially about its continuity and have serious problems with
    discontinuities. In the case of a dropped object, the second derivative is
    not zero at the ends, just at it does some extreme things with an impact.
    You cannot apply a smoothing algorithm _through_ an impact, no matter what
    order you use (and you dont want to). There is no algorithm for which you
    wont find examples of boundary conditions that cause it to generate
    misleading results. This is not a case of garbage in, garbage out. Cubic
    and quintic splines both work well when used properly and distort the data
    when not. It's just that there is no substitute for collecting and
    analyzing data thoughtfully.

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