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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2008 - INRIA
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
//
//
function x = hilbert(xr)
// Marple, S.L., "Computing the discrete-time analytic signal via FFT,"
// IEEE Transactions on Signal Processing, Vol. 47, No.9 (September
// 1999), pp.2600-2603
// http://ieeexplore.ieee.org/iel5/78/16975/00782222.pdf?arnumber=782222
if type(xr)<>1 then
error(msprintf(gettext("%s: Wrong type for input argument #%d: Array of floating point numbers expected.\n"),"hilbert",1))
end
n=size(xr,'*');
if n==0 then x=[],return,end
if ~isreal(xr,0) then
error(msprintf(gettext("%s: Input argument #%d must be real.\n"),'hilbert',1));
end
no2 = int(n/2);
x = fft(real(xr),-1);
h = zeros(xr);
if ((2*no2) == n) then // n is even
h([1,no2+1]) = 1;
h(2:no2) = 2;
else // n is odd
h(1) = 1;
h(2:(n+1)/2) = 2;
end
x = fft(x.*h,1);
endfunction
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