refactor(basis): remove NSolid NURBS volume basis

Drop unmaintained tensor-product solid NURBS tied to removed NURBS helpers.

src/basis/nurbs_solid.jl

@@ -1,59 +0,0 @@
-# This file is a part of JuliaFEM.
-# License is MIT: see https://github.com/JuliaFEM/jl/blob/master/LICENSE
-
-mutable struct NSolid <: AbstractBasis{3}
-    order_u :: Int
-    order_v :: Int
-    order_w :: Int
-    knots_u :: Vector{Float64}
-    knots_v :: Vector{Float64}
-    knots_w :: Vector{Float64}
-    weights :: Array{Float64, 3}
-end
-
-function NSolid()
-    NSolid(1, 1, 1,
-        [-1.0, -1.0, 1.0, 1.0],
-        [-1.0, -1.0, 1.0, 1.0],
-        [-1.0, -1.0, 1.0, 1.0],
-        ones(2, 2, 2))
-end
-
-function length(basis::NSolid)
-    nu = length(basis.knots_u) - basis.order_u - 1
-    nv = length(basis.knots_v) - basis.order_v - 1
-    nw = length(basis.knots_w) - basis.order_w - 1
-    return nu*nv*nw
-end
-
-function size(basis::NSolid)
-    return (3, length(basis))
-end
-
-function eval_basis!(basis::NSolid, N::Vector, xi::Vec{3})
-    pu = basis.order_u
-    pv = basis.order_v
-    pw = basis.order_w
-    tu = basis.knots_u
-    tv = basis.knots_v
-    tw = basis.knots_w
-    weights = basis.weights
-    nu = length(tu)-pu-1
-    nv = length(tv)-pv-1
-    nw = length(tw)-pw-1
-    u, v, w = xi
-    n = 1
-    for i=1:nu
-        for j=1:nv
-            for k=1:nw
-                A = NURBS(i,pu,u,tu)
-                B = NURBS(j,pv,v,tv)
-                C = NURBS(k,pw,w,tw)
-                N[n] = weights[i,j,k]*A*B*C
-                n += 1
-            end
-        end
-    end
-    N ./= sum(N)
-    return N
-end