function y = polyvaln(p, varargin)

% polyvaln -- Evalate an ND polynomial.
%  polyvaln(p, loc) evaluates polynomial p
%   at locations loc, a matrix whose columns
%   represent [x y z ...].  The  ND polynomial
%   is arranged as in "polyfitn".
%  polyvaln(p, x, y, z, ...) is an alternative
%   syntax.
%
% Also see: polyfitn.
 
% Copyright (C) 2003 Dr. Charles R. Denham, ZYDECO.
%  All Rights Reserved.
%   Disclosure without explicit written consent from the
%    copyright owner does not constitute publication.
 
% Version of 22-Apr-2003 14:51:04.
% Updated    22-Apr-2003 15:05:48.

if nargin < 2, help(mfilename), return, end

loc = [varargin{:}];

[m, n] = size(loc);
order = size(p, 2) - 1;
dims = length(size(p));
sz = size(p);

% Exponents for expansion.

sub = cell(1, dims);
[sub{:}] = ind2sub(sz, 1:prod(sz));
for i = 1:length(sub)
    sub{i} = sub{i}(:);
end
expon = [sub{:}] - 1;

% Trim exponents to requested order.

for k = 1:length(expon)
    if sum(expon(k, :)) > order
        expon(k, :) = NaN;
    end
end

y = zeros(m, 1);

k = 0;
for i = 1:prod(sz)
    k = k+1;
    ex = expon(k, :);
    if all(isfinite(ex))
        ex = repmat(ex, [m 1]);
        x = loc .^ ex;
        x = prod(x, 2);
        x = p(k) * x;
        y = y + x;
    end
end