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diff --git a/octave_packages/nurbs-1.3.6/nrbeval.m b/octave_packages/nurbs-1.3.6/nrbeval.m
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+++ b/octave_packages/nurbs-1.3.6/nrbeval.m
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+function [p,w] = nrbeval(nurbs,tt)
+% 
+% NRBEVAL: Evaluate a NURBS at parametric points.
+% 
+% Calling Sequences:
+% 
+%   [p,w] = nrbeval(crv,ut)
+%   [p,w] = nrbeval(srf,{ut,vt})
+%   [p,w] = nrbeval(vol,{ut,vt,wt})
+%   [p,w] = nrbeval(srf,pts)
+% 
+% INPUT:
+% 
+%   crv		: NURBS curve, see nrbmak.
+% 
+%   srf		: NURBS surface, see nrbmak.
+%
+%   vol		: NURBS volume, see nrbmak.
+% 
+%   ut		: Parametric evaluation points along U direction.
+%
+%   vt		: Parametric evaluation points along V direction.
+% 
+%   wt		: Parametric evaluation points along W direction.
+%
+%   pts     : Array of scattered points in parametric domain
+% 
+% OUTPUT:
+%
+%   p		: Evaluated points on the NURBS curve, surface or volume as 
+% 		Cartesian coordinates (x,y,z). If w is included on the lhs argument
+% 		list the points are returned as homogeneous coordinates (wx,wy,wz).
+% 
+%   w		: Weights of the homogeneous coordinates of the evaluated
+% 		points. Note inclusion of this argument changes the type 
+% 		of coordinates returned in p (see above).
+% 
+% Description:
+% 
+%   Evaluation of NURBS curves, surfaces or volume at parametric points along  
+%   the U, V and W directions. Either homogeneous coordinates are returned
+%   if the weights are requested in the lhs arguments, or as Cartesian coordinates.
+%   This function utilises the 'C' interface bspeval.
+% 
+% Examples:
+% 
+%   Evaluate the NURBS circle at twenty points from 0.0 to 1.0
+% 
+%   nrb = nrbcirc;
+%   ut = linspace(0.0,1.0,20);
+%   p = nrbeval(nrb,ut);
+% 
+% See also:
+%  
+%     bspeval
+%
+% Copyright (C) 2000 Mark Spink 
+% Copyright (C) 2010 Carlo de Falco
+% Copyright (C) 2010, 2011 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/>.
+
+if (nargin < 2)
+  error('Not enough input arguments');
+end
+
+foption = 1;    % output format 3D cartesian coordinates
+if (nargout == 2)
+  foption = 0;  % output format 4D homogenous coordinates 
+end
+   
+if (~isstruct(nurbs))
+  error('NURBS representation is not structure!');
+end
+
+if (~strcmp(nurbs.form,'B-NURBS'))
+  error('Not a recognised NURBS representation');
+end
+
+if (iscell(nurbs.knots))
+  if (size(nurbs.knots,2) == 3)
+    %% NURBS structure represents a volume
+
+    num1 = nurbs.number(1);
+    num2 = nurbs.number(2);
+    num3 = nurbs.number(3);
+    degree = nurbs.order-1;
+
+    if (iscell(tt))
+      nt1 = numel (tt{1});
+      nt2 = numel (tt{2});
+      nt3 = numel (tt{3});
+
+      %% evaluate along the w direction
+      val = reshape (nurbs.coefs, 4*num1*num2, num3);
+      val = bspeval (degree(3), val, nurbs.knots{3}, tt{3});
+      val = reshape (val, [4 num1 num2 nt3]);
+
+      %% Evaluate along the v direction
+      val = permute (val, [1 2 4 3]);
+      val = reshape (val, 4*num1*nt3, num2);
+      val = bspeval (degree(2), val, nurbs.knots{2}, tt{2});
+      val = reshape (val, [4 num1 nt3 nt2]);
+      val = permute (val, [1 2 4 3]);
+
+      %% Evaluate along the u direction
+      val = permute (val, [1 3 4 2]);
+      val = reshape (val, 4*nt2*nt3, num1);
+      val = bspeval (degree(1), val, nurbs.knots{1}, tt{1});
+      val = reshape (val, [4 nt2 nt3 nt1]);
+      val = permute (val, [1 4 2 3]);
+      pnts = val;
+
+      p = pnts(1:3,:,:,:);
+      w = pnts(4,:,:,:);
+      if (foption)
+        p = p./repmat(w,[3 1 1 1]);
+      end
+
+    else
+
+      %% Evaluate at scattered points
+      %% tt(1,:) represents the u direction
+      %% tt(2,:) represents the v direction
+      %% tt(3,:) represents the w direction
+
+      %% evaluate along the w direction
+      nt = size(tt,2);
+      val = reshape(nurbs.coefs,4*num1*num2,num3);
+      val = bspeval(degree(3),val,nurbs.knots{3},tt(3,:));
+      val = reshape(val,[4 num1 num2 nt]);
+
+      %% evaluate along the v direction
+      val2 = zeros(4*num1,nt);
+      for v = 1:nt
+        coefs = reshape(val(:,:,:,v),4*num1,num2);
+        val2(:,v) = bspeval(degree(2),coefs,nurbs.knots{2},tt(2,v));
+      end
+      val2 = reshape(val2,[4 num1 nt]);
+
+      %% evaluate along the u direction
+      pnts = zeros(4,nt);
+      for v = 1:nt
+        coefs = reshape (val2(:,:,v), [4 num1]);
+        pnts(:,v) = bspeval(degree(1),coefs,nurbs.knots{1},tt(1,v));
+      end
+
+      w = pnts(4,:);
+      p = pnts(1:3,:);
+      if (foption)
+        p = p./repmat(w,[3, 1]);
+      end
+    end
+
+  elseif (size(nurbs.knots,2) == 2)
+    %% NURBS structure represents a surface
+  
+    num1 = nurbs.number(1);
+    num2 = nurbs.number(2);
+    degree = nurbs.order-1;
+
+    if (iscell(tt))
+      %% Evaluate over a [u,v] grid
+      %% tt{1} represents the u direction
+      %% tt{2} represents the v direction
+
+      nt1 = length(tt{1});
+      nt2 = length(tt{2});
+    
+      %% Evaluate along the v direction
+      val = reshape(nurbs.coefs,4*num1,num2);
+      val = bspeval(degree(2),val,nurbs.knots{2},tt{2});
+      val = reshape(val,[4 num1 nt2]);
+    
+      %% Evaluate along the u direction
+      val = permute(val,[1 3 2]);
+      val = reshape(val,4*nt2,num1);
+      val = bspeval(degree(1),val,nurbs.knots{1},tt{1});
+      val = reshape(val,[4 nt2 nt1]);
+      val = permute(val,[1 3 2]);
+
+      w = val(4,:,:);
+      p = val(1:3,:,:);
+      if (foption)
+	p = p./repmat(w,[3 1 1]);
+      end
+
+    else
+
+      %% Evaluate at scattered points
+      %% tt(1,:) represents the u direction
+      %% tt(2,:) represents the v direction
+
+      nt = size(tt,2);
+
+      val = reshape(nurbs.coefs,4*num1,num2);
+      val = bspeval(degree(2),val,nurbs.knots{2},tt(2,:));
+      val = reshape(val,[4 num1 nt]);
+
+
+      %% evaluate along the u direction
+      pnts = zeros(4,nt);
+      for v = 1:nt
+	coefs = reshape (val(:,:,v), [4 num1]);
+	pnts(:,v) = bspeval(degree(1),coefs,nurbs.knots{1},tt(1,v));
+      end
+
+      w = pnts(4,:);
+      p = pnts(1:3,:);
+      if (foption)
+	p = p./repmat(w,[3, 1]);
+      end
+        
+    end
+
+  end
+else
+
+  %% NURBS structure represents a curve
+  %%  tt represent a vector of parametric points in the u direction
+  
+  val = bspeval(nurbs.order-1,nurbs.coefs,nurbs.knots,tt);   
+
+  w = val(4,:);
+  p = val(1:3,:);
+  if foption
+    p = p./repmat(w,3,1);
+  end
+
+end
+
+end
+
+%!demo
+%! srf = nrbtestsrf;
+%! p = nrbeval(srf,{linspace(0.0,1.0,20) linspace(0.0,1.0,20)});
+%! h = surf(squeeze(p(1,:,:)),squeeze(p(2,:,:)),squeeze(p(3,:,:)));
+%! title('Test surface.');
+%! hold off
+
+%!test
+%! knots{1} = [0 0 0 1 1 1];
+%! knots{2} = [0 0 0 .5 1 1 1];
+%! knots{3} = [0 0 0 0 1 1 1 1];
+%! cx = [0 0.5 1]; nx = length(cx);
+%! cy = [0 0.25 0.75 1]; ny = length(cy);
+%! cz = [0 1/3 2/3 1]; nz = length(cz);
+%! coefs(1,:,:,:) = repmat(reshape(cx,nx,1,1),[1 ny nz]);
+%! coefs(2,:,:,:) = repmat(reshape(cy,1,ny,1),[nx 1 nz]);
+%! coefs(3,:,:,:) = repmat(reshape(cz,1,1,nz),[nx ny 1]);
+%! coefs(4,:,:,:) = 1;
+%! nurbs = nrbmak(coefs, knots);
+%! x = rand(5,1); y = rand(5,1); z = rand(5,1);
+%! tt = [x y z]';
+%! points = nrbeval(nurbs,tt);
+%!
+%! assert(points,tt,1e-10)
+%!
+%!test
+%! knots{1} = [0 0 0 1 1 1];
+%! knots{2} = [0 0 0 0 1 1 1 1];
+%! knots{3} = [0 0 1 1];
+%! cx = [0 0 1]; nx = length(cx);
+%! cy = [0 0 0 1]; ny = length(cy);
+%! cz = [0 1]; nz = length(cz);
+%! coefs(1,:,:,:) = repmat(reshape(cx,nx,1,1),[1 ny nz]);
+%! coefs(2,:,:,:) = repmat(reshape(cy,1,ny,1),[nx 1 nz]);
+%! coefs(3,:,:,:) = repmat(reshape(cz,1,1,nz),[nx ny 1]);
+%! coefs(4,:,:,:) = 1;
+%! nurbs = nrbmak(coefs, knots);
+%! x = rand(5,1); y = rand(5,1); z = rand(5,1);
+%! tt = [x y z]';
+%! points = nrbeval(nurbs,tt);
+%! assert(points,[x.^2 y.^3 z]',1e-10);
+%!
+%!test
+%! knots{1} = [0 0 0 1 1 1];
+%! knots{2} = [0 0 0 0 1 1 1 1];
+%! knots{3} = [0 0 1 1];
+%! cx = [0 0 1]; nx = length(cx);
+%! cy = [0 0 0 1]; ny = length(cy);
+%! cz = [0 1]; nz = length(cz);
+%! coefs(1,:,:,:) = repmat(reshape(cx,nx,1,1),[1 ny nz]);
+%! coefs(2,:,:,:) = repmat(reshape(cy,1,ny,1),[nx 1 nz]);
+%! coefs(3,:,:,:) = repmat(reshape(cz,1,1,nz),[nx ny 1]);
+%! coefs(4,:,:,:) = 1;
+%! coefs = coefs([2 1 3 4],:,:,:);
+%! nurbs = nrbmak(coefs, knots);
+%! x = rand(5,1); y = rand(5,1); z = rand(5,1);
+%! tt = [x y z]';
+%! points = nrbeval(nurbs,tt);
+%! [y.^3 x.^2 z]';
+%! assert(points,[y.^3 x.^2 z]',1e-10);