--- /dev/null
+function [B, id] = nrbbasisfun (points, nrb)
+
+% NRBBASISFUN: Basis functions for NURBS
+%
+% Calling Sequence:
+%
+% B = nrbbasisfun (u, crv)
+% B = nrbbasisfun ({u, v}, srf)
+% [B, N] = nrbbasisfun ({u, v}, srf)
+% [B, N] = nrbbasisfun (p, srf)
+%
+% INPUT:
+%
+% u or p(1,:,:) - parametric points along u direction
+% v or p(2,:,:) - parametric points along v direction
+% crv - NURBS curve
+% srf - NURBS surface
+%
+% OUTPUT:
+%
+% B - Value of the basis functions at the points
+% size(B)=[numel(u),(p+1)] for curves
+% or [numel(u)*numel(v), (p+1)*(q+1)] for surfaces
+%
+% N - Indices of the basis functions that are nonvanishing at each
+% point. size(N) == size(B)
+%
+%
+% Copyright (C) 2009 Carlo de Falco
+%
+% This program is free software: you can redistribute it and/or modify
+% it under the terms of the GNU General Public License as published by
+% the Free Software Foundation, either version 2 of the License, or
+% (at your option) any later version.
+
+% This program is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ if ( (nargin<2) ...
+ || (nargout>2) ...
+ || (~isstruct(nrb)) ...
+ || (iscell(points) && ~iscell(nrb.knots)) ...
+ || (~iscell(points) && iscell(nrb.knots) && (size(points,1)~=2)) ...
+ || (~iscell(nrb.knots) && (nargout>1)) ...
+ )
+ error('Incorrect input arguments in nrbbasisfun');
+ end
+
+ if (~iscell(nrb.knots)) %% NURBS curve
+
+ [B, id] = nrb_crv_basisfun__ (points, nrb);
+
+ elseif size(nrb.knots,2) == 2 %% NURBS surface
+ if (iscell(points))
+ [v, u] = meshgrid(points{2}, points{1});
+ p = [u(:), v(:)]';
+ else
+ p = points;
+ end
+
+ [B, id] = nrb_srf_basisfun__ (p, nrb);
+
+ else %% NURBS volume
+ error('The function nrbbasisfun is not yet ready for volumes')
+ end
+end
+
+%!demo
+%! U = [0 0 0 0 1 1 1 1];
+%! x = [0 1/3 2/3 1] ;
+%! y = [0 0 0 0];
+%! w = [1 1 1 1];
+%! nrb = nrbmak ([x;y;y;w], U);
+%! u = linspace(0, 1, 30);
+%! B = nrbbasisfun (u, nrb);
+%! xplot = sum(bsxfun(@(x,y) x.*y, B, x),2);
+%! plot(xplot, B)
+%! title('Cubic Bernstein polynomials')
+%! hold off
+
+%!test
+%! U = [0 0 0 0 1 1 1 1];
+%! x = [0 1/3 2/3 1] ;
+%! y = [0 0 0 0];
+%! w = rand(1,4);
+%! nrb = nrbmak ([x;y;y;w], U);
+%! u = linspace(0, 1, 30);
+%! B = nrbbasisfun (u, nrb);
+%! xplot = sum(bsxfun(@(x,y) x.*y, B, x),2);
+%!
+%! yy = y; yy(1) = 1;
+%! nrb2 = nrbmak ([x.*w;yy;y;w], U);
+%! aux = nrbeval(nrb2,u);
+%! %figure, plot(xplot, B(:,1), aux(1,:).', w(1)*aux(2,:).')
+%! assert(B(:,1), w(1)*aux(2,:).', 1e-6)
+%!
+%! yy = y; yy(2) = 1;
+%! nrb2 = nrbmak ([x.*w;yy;y;w], U);
+%! aux = nrbeval(nrb2, u);
+%! %figure, plot(xplot, B(:,2), aux(1,:).', w(2)*aux(2,:).')
+%! assert(B(:,2), w(2)*aux(2,:).', 1e-6)
+%!
+%! yy = y; yy(3) = 1;
+%! nrb2 = nrbmak ([x.*w;yy;y;w], U);
+%! aux = nrbeval(nrb2,u);
+%! %figure, plot(xplot, B(:,3), aux(1,:).', w(3)*aux(2,:).')
+%! assert(B(:,3), w(3)*aux(2,:).', 1e-6)
+%!
+%! yy = y; yy(4) = 1;
+%! nrb2 = nrbmak ([x.*w;yy;y;w], U);
+%! aux = nrbeval(nrb2,u);
+%! %figure, plot(xplot, B(:,4), aux(1,:).', w(4)*aux(2,:).')
+%! assert(B(:,4), w(4)*aux(2,:).', 1e-6)
+
+%!test
+%! p = 2; q = 3; m = 4; n = 5;
+%! Lx = 1; Ly = 1;
+%! nrb = nrb4surf ([0 0], [1 0], [0 1], [1 1]);
+%! nrb = nrbdegelev (nrb, [p-1, q-1]);
+%! aux1 = linspace(0,1,m); aux2 = linspace(0,1,n);
+%! nrb = nrbkntins (nrb, {aux1(2:end-1), aux2(2:end-1)});
+%! u = rand (1, 30); v = rand (1, 10);
+%! u = u - min (u); u = u / max (u);
+%! v = v - min (v); v = v / max (v);
+%! [B, N] = nrbbasisfun ({u, v}, nrb);
+%! assert (sum(B, 2), ones(300, 1), 1e-6)
+%! assert (all (all (B<=1)), true)
+%! assert (all (all (B>=0)), true)
+%! assert (all (all (N>0)), true)
+%! assert (all (all (N <= prod (nrb.number))), true)
+%! assert (max (max (N)),prod (nrb.number))
+%! assert (min (min (N)),1)
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