--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main/splines/ppval.m	Wed Oct 10 19:54:49 2001 +0000
@@ -0,0 +1,48 @@
+## Copyright (C) 2000 Paul Kienzle
+##
+## 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, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## usage: yi = ppval(pp, xi)
+## Evaluate piece-wise polynomial pp and points xi.  If pp.d > 1,
+## the returned yi will be a matrix of size rows(xi) by pp.d, or
+## its transpose if xi is a row vector.
+
+function yi = ppval(pp, xi)
+  if nargin != 2
+    usage("yi = ppval(pp, xi)")
+  endif
+  if !isstruct(pp)
+    error("ppval: expects a pp structure");
+  endif
+  if (isempty (xi))
+    yi = [];
+  else
+    transposed = (rows(xi) == 1);
+    [nr, nc] = size(xi);
+    xi = xi(:);
+    idx = lookup(pp.x(2:pp.n), xi) + 1;
+    dx = xi - pp.x(idx);
+    dx = dx(:,ones(1,pp.d));
+    c = reshape (pp.P(:, 1), pp.n, pp.d);
+    yi = c(idx, :);
+    for i  = 2 : pp.k;
+      c = reshape (pp.P(:, i), pp.n, pp.d);
+      yi = yi .* dx + c(idx, :);
+    endfor
+    if (transposed)
+      yi = yi.';
+    endif
+  endif
+endfunction