Diff of /inst/ddmat.m [000000] .. [77d7c2] Maximize Restore

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+++ b/inst/ddmat.m
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+function D = ddmat(x, d)
+%%function D = ddmat(x, d)
+%% Compute divided differencing matrix of order d
+%%
+%% Input
+%%   x:  vector of sampling positions
+%%   d:  order of diffferences
+%% Output
+%%   D:  the matrix; D * Y gives divided differences of order d
+%%
+%%References:  Anal. Chem. (2003) 75, 3631.
+%%  
+
+%% corrected the recursion multiplier; JJS 2/25/08
+
+%% Copyright (C) 2003 Paul Eilers
+%% 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/>. 
+
+
+m = length(x);
+if d == 0
+    D = speye(m);
+else
+    dx = x((d + 1):m) - x(1:(m - d));
+    V = spdiags(1 ./ dx, 0, m - d, m - d);
+    D = d * V * diff(ddmat(x, d - 1));
+end