Error using ==> mtimes Inner matrix dimensions must agree.

    % Magnitude spectrum computation (as column vectors)
    MAG = abs( fft(frames,nfft,1) ); 

    % Triangular filterbank with uniformly spaced filters on mel scale
    H = trifbank( M, K, R, fs, hz2mel, mel2hz ); % size of H is M x K 

    % Filterbank application to unique part of the magnitude spectrum
    FBE = H * MAG(1:K,:); % FBE( FBE<1.0 ) = 1.0; % apply mel floor

    % DCT matrix computation
    DCT = dctm( N, M );

    % Conversion of logFBEs to cepstral coefficients through DCT
    CC =  DCT *log( FBE );

It shows the error: Error using ==> mtimes Inner matrix dimensions must agree.

Error in ==> new at 47 CC = DCT *log( FBE );

Answer 1

[Wayne King]

What are the sizes of DCT and FBE? This error is simply telling you that your matrices are not conformable for multiplication like the following:

   X = randn(2,3);
   Y = randn(2,3);
   X*Y

It may be a simple matter of just transposing one matrix, but that is impossible for us to say.