Write a self contained program which will take a signal and compute its Cosine transform

I'm new to MATLAB and was wondering if anyone could help me with this problem? I don't know where to start.

Write a self contained program which will take a signal and compute its Cosine transform. Have the program decide how many significant coefficients are necessary for a given input tolerance (such as .01, or .001).

[Walter Roberson]

What does "self contained" mean in this case?

http://www.mathworks.com/matlabcentral/answers/38787-what-can-be-programmed-without-any-built-in-functions

[Amy Peters]

I think I'm allowed to use the "built-in functions" in this question. I just don't know how to start writing something that would allow me to take the cosine transform. Would I use dct(x,n)?

Answer 1

[Walter Roberson]

You use a "for" loop from 0 to half of the number of points. In each one, you use a vectorized cos() calculation and add the vector of results to your running total. Like

total = zeros(size(x));
for K = 1 : 5
  total = total + cos(f(x,K));
end

for some f(x,K)