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// Copyright (C) 2018 - IIT Bombay - FOSSEE
//
// 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
// Original Source : https://octave.sourceforge.io/signal/
// Modifieded by:Sonu Sharma, RGIT Mumbai
// Organization: FOSSEE, IIT Bombay
// Email: toolbox@scilab.in
function T = dctmtx(n)
// Return the DCT transformation matrix of size N-by-N.
//Calling Sequence
//T = dctmtx(n)
//Parameters
//n: Real scalar integer greater than or equal to 1
//Description
//dctmtx(n) returns a Discrete cosine transform matrix (D) of order n-by-n. It is useful for jpeg image compression. D*A is the DCT of the columns of A and D'*A is the inverse DCT of the columns of A (when A is n-by-n).
// Examples
//n= 3;
//T = dctmtx(n)
//Output:
// T =
//
// 0.5773503 0.5773503 0.5773503
// 0.7071068 5.000D-17 - 0.7071068
// 0.4082483 - 0.8164966 0.4082483
funcprot();
[nargout nargin] = argn();
if nargin ~= 1
error("dctmtx: invalid number of inputs")
end
if n > 1
T = [ sqrt(1/n)*ones(1,n) ; ...
sqrt(2/n)*cos((%pi/2/n)*([1:n-1]'*[1:2:2*n])) ];
elseif n == 1
T = 1;
else
error ("dctmtx: n must be at least 1");
end
endfunction
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