On 2/15/23 06:50, Simon wrote:
my objective is to do an 1d-approximation
F(x) = N_i(x) P_i
where N_i are cubic B-spline basis functions and P_i known nodal values
(control points).
To assemble my linear system, I have to compute the first and second
derivatives of F at the quadrature points of the triangulation.
Since the number of control points P_i is quite moderate (less than 20), I
think it is reasonable to evaluate all basis functions N_i in lieu of
implementing an entire finite element class.
I scanned the dealii manual but could only find a CSpline class
<https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.dealii.org%2Fcurrent%2Fdoxygen%2Fdeal.II%2FclassFunctions_1_1CSpline.html&data=05%7C01%7CWolfgang.Bangerth%40colostate.edu%7C9ac052e12d814289384108db0f5b957c%7Cafb58802ff7a4bb1ab21367ff2ecfc8b%7C0%7C0%7C638120658249146546%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=NqcY%2FpN5QJnuhVYWG3BiLLKxYUZIZNyYDCKKEDq3iYI%3D&reserved=0>.
Just to make sure:
B-Spline (basis) functions are not implemented in dealii yet, right?
Simon -- that is correct. I suspect (but don't know) that you also want to use
spline basis functions that span across more than one cell; that is an
uncommon operation for finite element libraries and there is not much support
implemented for these kinds of things -- in particular, there are none of the
spline basis functions one might use for this.
Best
W.
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Wolfgang Bangerth email: bange...@colostate.edu
www: http://www.math.colostate.edu/~bangerth/
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