Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/nurbs-1.3.6/kntbrkdegmult.m b/octave_packages/nurbs-1.3.6/kntbrkdegmult.m
new file mode 100644 (file)
index 0000000..7ab0078
--- /dev/null
+++ b/octave_packages/nurbs-1.3.6/kntbrkdegmult.m
@@ -0,0 +1,122 @@
+% KNTBRKDEGMULT: Construct an open knot vector by giving the sequence of
+%                knots, the degree and the multiplicity.
+%
+%   knots = kntbrkdegreg (breaks, degree)
+%   knots = kntbrkdegreg (breaks, degree, mult)
+%
+% INPUT:
+%
+%     breaks:  sequence of knots.
+%     degree:  polynomial degree of the splines associated to the knot vector.
+%     mult:    multiplicity of the knots.
+%
+% OUTPUT:
+%
+%     knots:  knot vector.
+%
+% If MULT has as many entries as BREAKS, or as the number of interior
+%   knots, a different multiplicity will be assigned to each knot. If
+%   MULT is not present, it will be taken equal to 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 = kntbrkdegmult (breaks, degree, mult)
+
+  if (iscell (breaks))
+    if (nargin == 2)
+      mult = 1;
+    end
+  
+    if (numel(breaks)~=numel(degree) || numel(breaks)~=numel(mult))
+      error('kntbrkdegmult: degree and multiplicity must have the same length as the number of knot vectors')
+    end
+
+    degree = num2cell (degree);
+
+    if (~iscell (mult))
+      mult = num2cell (mult);
+    end
+
+    knots = cellfun (@do_kntbrkdegmult, breaks, degree, mult, 'uniformoutput', false);
+
+  else
+
+    if (nargin == 2)
+      mult = 1;
+    end
+
+    knots = do_kntbrkdegmult (breaks, degree, mult);
+  end
+end
+
+  
+function knots = do_kntbrkdegmult (breaks, degree, mult)  
+
+if (numel (breaks) < 2)
+  error ('kntbrkdegmult: the knots sequence should contain at least two points')
+end
+
+if (numel (mult) == 1)
+  mults = [degree+1, mult(ones (1, numel (breaks) - 2)), degree+1];
+elseif (numel (mult) == numel (breaks))
+  mults = [degree+1 mult(2:end-1) degree+1];
+elseif (numel (mult) == numel (breaks) - 2)
+  mults = [degree+1 mult degree+1];
+else
+  error('kntbrkdegmult: the length of mult should be equal to one or the number of knots')
+end
+
+if (any (mults > degree+1))
+  warning ('kntbrkdegmult: some knots have higher multiplicity than the degree+1')
+end
+
+breaks = sort (breaks);
+
+lm = numel (mults);
+sm = sum (mults);
+
+mm = zeros (1,sm);
+mm (cumsum ([1 reshape(mults (1:end-1), 1, lm-1)])) = ones (1,lm);
+knots = breaks (cumsum (mm));
+
+end
+
+%!test
+%! breaks = [0 1 2 3 4];
+%! degree = 3;
+%! knots = kntbrkdegmult (breaks, degree);
+%! assert (knots, [0 0 0 0 1 2 3 4 4 4 4])
+
+%!test
+%! breaks = [0 1 2 3 4];
+%! degree = 3;
+%! mult   = 2;
+%! knots = kntbrkdegmult (breaks, degree, mult);
+%! 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;
+%! mult   = [1 2 3];
+%! knots = kntbrkdegmult (breaks, degree, mult);
+%! assert (knots, [0 0 0 0 1 2 2 3 3 3 4 4 4 4])
+
+%!test
+%! breaks = {[0 1 2 3 4] [0 1 2 3]};
+%! degree = [3 2];
+%! mult   = {[1 2 3] 2};
+%! knots = kntbrkdegmult (breaks, degree, mult);
+%! assert (knots, {[0 0 0 0 1 2 2 3 3 3 4 4 4 4] [0 0 0 1 1 2 2 3 3 3]})