Is there a function in MATLAB to calculate higher DCTs like DCT-III, IV etc?

I have started learning DCT recently. I know the function dct() and dct2() are used to calculated 1-D and 2-D DCT-II repectively. Is there any function that is used to calculate the DCT-III or DCT-IV? idct() is based on DCT-III but it is not going forward into DCT domain.

Answer 1

[Matt J]

You can check the File Exchange, e.g.,

https://www.mathworks.com/matlabcentral/fileexchange/24050-multidimensional-discrete-cosine-transform-dct?s_tid=srchtitle

https://www.mathworks.com/matlabcentral/fileexchange/26040-dct-and-dst-inverse-in-arbitrary-dimension?s_tid=srchtitle

Answer 2

[Matt J]

I don't think so, but you can always build one from fft().

function Y=dctn(X)

    d=size(X);
    n=numel(d);
    subs0=repmat({':'},1,n);
    
 Y=X;
 for i=1:n
     
     subs=subs0;
     subs{i}=1:d(i);
     
     Y=fft( cat(i,Y,flip(Y,i))  ,[],i);
     Y=real(Y(subs{:});
     
 end
  

end