/usr/share/octave/packages/nurbs-1.3.10/nrb4surf.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 | function srf = nrb4surf(p11,p12,p21,p22)
%
% NRB4SURF: Constructs a NURBS bilinear surface.
%
% Calling Sequence:
%
% srf = nrb4surf(p11,p12,p21,p22)
%
% INPUT:
%
% p11 : Cartesian coordinate of the lhs bottom corner point.
%
% p12 : Cartesian coordinate of the rhs bottom corner point.
%
% p21 : Cartesian coordinate of the lhs top corner point.
%
% p22 : Cartesian coordinate of the rhs top corner point.
%
% OUTPUT:
%
% srf : NURBS bilinear surface, see nrbmak.
%
% Description:
%
% Constructs a bilinear surface defined by four coordinates.
%
% The position of the corner points
%
% ^ V direction
% |
% ----------------
% |p21 p22|
% | |
% | SRF |
% | |
% |p11 p12|
% -------------------> U direction
%
%
% Copyright (C) 2000 Mark Spink
%
% 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 ~= 4
error('Four corner points must be defined');
end
coefs = cat (1, zeros (3,2,2), ones (1,2,2));
coefs(1:length(p11),1,1) = p11(:);
coefs(1:length(p12),2,1) = p12(:);
coefs(1:length(p21),1,2) = p21(:);
coefs(1:length(p22),2,2) = p22(:);
knots = {[0 0 1 1] [0 0 1 1]};
srf = nrbmak(coefs, knots);
end
%!demo
%! srf = nrb4surf([0.0 0.0 0.5],[1.0 0.0 -0.5],[0.0 1.0 -0.5],[1.0 1.0 0.5]);
%! nrbplot(srf,[10,10]);
%! title('Construction of a bilinear surface.');
%! hold off
|