Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / nurbs-1.3.6 / kntbrkdegreg.m

diff --git a/octave_packages/nurbs-1.3.6/kntbrkdegreg.m b/octave_packages/nurbs-1.3.6/kntbrkdegreg.m
new file mode 100644 (file)
index 0000000..a3a12f6
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+++ b/octave_packages/nurbs-1.3.6/kntbrkdegreg.m
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+% KNTBRKDEGREG: Construct an open knot vector by giving the sequence of
+%                knots, the degree and the regularity.
+%
+%   knots = kntbrkdegreg (breaks, degree)
+%   knots = kntbrkdegreg (breaks, degree, regularity)
+%
+% INPUT:
+%
+%     breaks:     sequence of knots.
+%     degree:     polynomial degree of the splines associated to the knot vector.
+%     regularity: splines regularity.
+%
+% OUTPUT:
+%
+%     knots:  knot vector.
+%
+% If REGULARITY has as many entries as BREAKS, or as the number of interior
+%   knots, a different regularity will be assigned to each knot. If
+%   REGULARITY is not present, it will be taken equal to DEGREE-1.
+%
+% Copyright (C) 2010 Carlo de Falco, Rafael Vazquez
+%
+%    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/>.
+
+function knots = kntbrkdegreg (breaks, degree, reg)
+
+if (iscell (breaks))
+  if (nargin == 2)
+    reg = degree - 1;
+  end
+  
+  if (numel(breaks)~=numel(degree) || numel(breaks)~=numel(reg))
+    error('kntbrkdegreg: degree and regularity must have the same length as the number of knot vectors')
+  end
+
+  degree = num2cell (degree);
+
+  if (~iscell (reg))
+    reg = num2cell (reg);
+  end
+
+  knots = cellfun (@do_kntbrkdegreg, breaks, degree, reg, 'uniformoutput', false);
+else
+
+  if (nargin == 2)
+    reg = degree - 1;
+  end
+
+  knots = do_kntbrkdegreg (breaks, degree, reg);
+end
+
+end
+
+function knots = do_kntbrkdegreg (breaks, degree, reg)
+
+if (numel (breaks) < 2)
+  error ('kntbrkdegreg: the knots sequence should contain at least two points') 
+end
+
+if (numel (reg) == 1)
+  mults = [-1, (degree (ones (1, numel (breaks) - 2)) - reg), -1];
+elseif (numel (reg) == numel (breaks))
+  mults = degree - reg;
+elseif (numel (reg) == numel (breaks) - 2)
+  mults = [-1 degree-reg -1];
+else
+  error('kntbrkdegreg: the length of mult should be equal to one or the number of knots')
+end
+
+if (any (reg < -1))
+  warning ('kntbrkdegreg: for some knots the regularity is lower than -1')
+elseif (any (reg > degree-1))
+  error('kntbrkdegreg: the regularity should be lower than the degree')
+end
+
+knots = kntbrkdegmult (breaks, degree, mults);
+
+end
+
+%!test
+%! breaks = [0 1 2 3 4];
+%! degree = 3;
+%! knots = kntbrkdegreg (breaks, degree);
+%! assert (knots, [0 0 0 0 1 2 3 4 4 4 4])
+
+%!test
+%! breaks = [0 1 2 3 4];
+%! degree = 3;
+%! reg    = 1;
+%! knots = kntbrkdegreg (breaks, degree, reg);
+%! assert (knots, [0 0 0 0 1 1 2 2 3 3 4 4 4 4])
+
+%!test
+%! breaks = [0 1 2 3 4];
+%! degree = 3;
+%! reg    = [0 1 2];
+%! knots = kntbrkdegreg (breaks, degree, reg);
+%! assert (knots, [0 0 0 0 1 1 1 2 2 3 4 4 4 4])
+
+%!test
+%! breaks = {[0 1 2 3 4] [0 1 2 3]};
+%! degree = [3 2];
+%! reg    = {[0 1 2] 0};
+%! knots = kntbrkdegreg (breaks, degree, reg);
+%! assert (knots, {[0 0 0 0 1 1 1 2 2 3 4 4 4 4] [0 0 0 1 1 2 2 3 3 3]})
+