Stefan van der Walt wrote: >On Thu, Mar 22, 2007 at 04:33:53PM -0700, Travis Oliphant wrote: > > >>>I would rather opt for changing the spline fitting algorithm than for >>>padding with zeros. >>> >>> >>> >>> >> From what I understand, the splines used in ndimage have the implicit >>mirror-symmetric boundary condition which also allows them to be >>computed rapidly. There may be ways to adapt other boundary conditions >>and maintain rapid evaluation, but it is not trivial as far as I know. >>Standard spline-fitting allows multiple boundary conditions because >>matrix inversion is used. I think the spline-fitting done in ndimage >>relies on equal-spacing and mirror-symmetry to allow simple IIR filters >>to be used to compute the spline coefficients very rapidly. >> >> > >Thanks, Travis. I wasn't aware of these restrictions. > >Would it be possible to call fitpack to do the spline fitting? I >noticed that it doesn't exhibit the same mirror-property: > > It doesn't. It uses standard spline-fitting techniques (which are also slower). So, yes you could call fitpack but for a large multi-dimensional array it's going to take longer.
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