/usr/share/octave/packages/nurbs-1.3.10/nrbnumbasisfun.m is in octave-nurbs 1.3.10-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 | 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 3 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)
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