--- /dev/null
+function idx = nrbnumbasisfun (points, nrb)
+%
+% NRBNUMBASISFUN: Numbering of basis functions for NURBS
+%
+% Calling Sequence:
+%
+% N = nrbnumbasisfun (u, crv)
+% N = nrbnumbasisfun ({u, v}, srf)
+% N = nrbnumbasisfun (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:
+%
+% 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>1) ...
+ || (~isstruct(nrb)) ...
+ || (iscell(points) && ~iscell(nrb.knots)) ...
+ || (~iscell(points) && iscell(nrb.knots) && (size(points,1)~=2)) ...
+ )
+ error('Incorrect input arguments in nrbnumbasisfun');
+ end
+
+
+ if (~iscell(nrb.knots)) %% NURBS curve
+
+ iv = findspan (nrb.number-1, nrb.order-1, points, nrb.knots);
+ idx = numbasisfun (iv, points, nrb.order-1, nrb.knots);
+
+ elseif size(nrb.knots,2) == 2 %% NURBS surface
+
+ if (iscell(points))
+ [v, u] = meshgrid(points{2}, points{1});
+ p(1,:,:) = u;
+ p(2,:,:) = v;
+ p = reshape(p, 2, []);
+ else
+ p = points;
+ end
+
+ idx = nrb_srf_numbasisfun__ (p, nrb);
+ else
+ error('The function nrbnumbasisfun is not yet ready for volumes')
+ end
+
+end
+
+
+%!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]);
+%! ikx = linspace(0,1,m); iky = linspace(0,1,n);
+%! nrb = nrbkntins (nrb, {ikx(2:end-1), iky(2:end-1)});
+%! nrb.coefs (4,:,:) = nrb.coefs (4,:,:) + rand (size (nrb.coefs (4,:,:)));
+%! u = rand (1, 30); v = rand (1, 10);
+%! u = (u-min (u))/max (u-min (u));
+%! v = (v-min (v))/max (v-min (v));
+%! N = nrbnumbasisfun ({u, v}, nrb);
+%! 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)
\ No newline at end of file