% % Search value 'v' in sorted vector 'x' and find index and value
% % with respect to vector x that is equal or closest to 'v'.
% %
% % If more than one value is equal then anyone can be returned
% % (this is property of binary search).
% % If more than one value is closest then first occurred is returned
% % (this is property of linear search).
% %
% %
% % Algorithm
% % First binary search is used to find v in x. If not found
% % then range obtained by binary search is searched linearly
% % to find the closest value.
% %
% % INPUT:
% % x: vector of numeric values,
% % x should already be sorted in ascending order
% %    (e.g. 2,7,20,...120)
% % v: numeric value to be search in x
% %
% % OUTPUT:
% % i: index of v with respect to x.
% % cv: value that is equal or closest to v in x
%
% Copyright (c) 2009, Dr. Murtaza Khan
% All rights reserved.
%
% Redistribution and use in source and binary forms, with or without
% modification, are permitted provided that the following conditions are
% met:
%
%     * Redistributions of source code must retain the above copyright
%       notice, this list of conditions and the following disclaimer.
%     * Redistributions in binary form must reproduce the above copyright
%       notice, this list of conditions and the following disclaimer in
%       the documentation and/or other materials provided with the distribution
%
% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
% POSSIBILITY OF SUCH DAMAGE.

function [i,cv] = searchclosest(x,v)

i=[];
from=1;
to=length(x);

% % Phase 1: Binary Search
while from<=to
    mid = round((from + to)/2);
    diff = x(mid)-v;
    if diff==0
        i=mid;
        cv=v;
        return
    elseif diff<0     % x(mid) < v
        from=mid+1;
    else              % x(mid) > v
        to=mid-1;
    end
end


% ------ <bugfix> -------
% corrects problem if the 'from' has gone over the size of the vector 
% (due to +1 increment in binary search), fixed by 
% olaf.dimigen@hu-berlin.de for the version included in EYE-EEG toolbox,
% based on a bug report by Anton A. (thanks!)
if from > length(x)
    from = length(x);
end
% ------ </bugfix> -------

% % Phase 2: Linear Search
% % Remember Binary search could not find the value in x
% % Therefore from > to. Search range is to:from
y=x(to:from);             %vector to be searched for closest value
[ignore,mini]=min(abs(y-v));
cv=y(mini);
% % cv: closest value
% % mini: local index of minium (closest) value with respect to y

% % find global index of closest value with respect to x
i=to+mini-1;

% --------------------------------
% Author: Dr. Murtaza Khan
% Email : drkhanmurtaza@gmail.com
% -------------------------------