refactor(basis): remove NSeg NURBS segment basis

Delete unmaintained nurbs_segment.jl tied to removed NURBS helpers.

src/basis/nurbs_segment.jl

@@ -1,37 +0,0 @@
-# This file is a part of JuliaFEM.
-# License is MIT: see https://github.com/JuliaFEM/jl/blob/master/LICENSE
-
-""" NURBS segment. """
-mutable struct NSeg <: AbstractBasis{1}
-    order :: Int
-    knots :: Vector{Float64}
-    weights :: Vector{Float64}
-end
-
-function NSeg()
-    NSeg(1,
-        [-1.0, -1.0, 1.0, 1.0],
-        ones(4))
-end
-
-function length(basis::NSeg)
-    nu = length(basis.knots) - basis.order - 1
-    return nu
-end
-
-function size(basis::NSeg)
-    return (1, length(basis))
-end
-
-function eval_basis!(basis::NSeg, N::Vector, xi::Vec{1})
-    pu = basis.order
-    tu = basis.knots
-    w = basis.weights
-    nu = length(tu)-pu-1
-    u = xi[1]
-    for j=1:nu
-        N[j] = w[j]*NURBS(j,pu,u,tu)
-    end
-    N ./= sum(N)
-    return N
-end