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Please help me convert equation to matlab code.

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N K on 15 Feb 2012
Edited: Greg Heath on 13 Oct 2013
Deal all.
I need you help to convert this equation to matlab code to plot DCT basis function graph.
Equation is in
at equation (1) and (2).
*I'm not a student in this class but I need DCT concept to write code.
I spend a lot of time to write it but it doesn't work.
Please help me. I must have DCT basis function for my work.
Best regard.
ps. If you have DCT basis function, please share it to me.

Answers (1)

Matt Tearle
Matt Tearle on 15 Feb 2012
Assuming that x is a column vector
N = length(x);
k = 0:(N-1);
DCTbasis = cos(k'*(2*k+1)*pi/(2*N));
w = sqrt(2/N)*DCTbasis*x;
w(1) = w(1)/sqrt(2);
will do the job. If you have Signal Processing Toolbox, so will
w = dct(x);
Matt Tearle
Matt Tearle on 15 Feb 2012
I'm not sure what you're trying to achieve with your follow-up question. It looks a lot like Q 1.1 in the lab, but you already found a nice visualization. I don't see what recreating the visualization in MATLAB will gain you -- it's messy because the visualization is plotting the underlying continuous function, not just the 8 sample points. If you run the code I gave, with x being any 8-by-1 vector, then the rows of the DCTbasis matrix will be the values of the basis functions, at the sample locations.

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