Hi Kyle, Looking at the internals, I think that one may get a B-spline by constructing a Spline1D with coefficients [0,,…,0,1,0,…,0], with 1 in the ith place for B_i, then evaluating it. But I am unsure of the role of bc and fp in the evaluation (if any).
My impression is that Dierckx is a library that does the fitting for given functions, which is fine since specialized algorithms exist for that, but OTOH for finite element methods one needs the basis matrices. Maybe I will port a B-spline basis generator, one can do it in around 50 LOC but it is full of corner cases (knots coinciding etc), so it would need quite a bit of testing. Maybe a Google SOC project for someone :D Best, Tamas On Sun, Apr 05 2015, Kyle Barbary <[email protected]> wrote: > Hi Tamas, > > I'm not familiar with R's splineDesign, so I'm not sure this helps, but you > can get internal spline coefficients in Dierckx with `get_coeffs(spl)` > where `spl` is a Spline1D object. Or look into the internals here: > https://github.com/kbarbary/Dierckx.jl/blob/master/src/Dierckx.jl#L83 . > > - Kyle > > On Sat, Apr 4, 2015 at 12:54 PM, Tamas Papp <[email protected]> wrote: > >> I have looked at Dierckx.jl, but could not figure out how to evaluate >> the B-spline basis (all the functions in the documentation appear to do >> fitting directly). Can you please give me a hint? >> >> Thanks, >> >> Tamas >> >> On Sat, Apr 04 2015, pauld11718 <[email protected]> wrote: >> >> > https://github.com/kbarbary/Dierckx.jl >> > >> > https://docs.scipy.org/doc/scipy-0.15.1/reference/interpolate.html >> > (use with PyCall) >> > >> > https://github.com/lgautier/Rif.jl >> > (R and Julia Interfacing) >> > >> > On Sunday, April 5, 2015 at 12:57:28 AM UTC+5:30, Tamas Papp wrote: >> >> >> >> Hi, >> >> >> >> I am looking for a function (library) that allows evaluation of a >> B-spline >> >> basis (specified by the knots and the order), at given points, _and_ >> >> also allows the evaluation of derivatives for the same family. R's >> >> splineDesign in the splines package has this, but looking at the splines >> >> libraries in Julia I could not find one that does B-splines and >> >> derivatives. Using internals from some library would be fine, too. >> >> >> >> (Knowing that there is no such thing at the moment would also be useful, >> >> I might implement it, but would prefer to avoid that because B-spline >> >> special cases are tricky). >> >> >> >> Best, >> >> >> >> Tamas >> >> >> >>
