code: def dctmat(N,K,freqstep,orthogonalize=True):
      
      cosmat = numpy.zeros((N, K), 'double')
      for n in range(0,N):
          for k in range(0, K):
              cosmat[n,k] = numpy.cos(freqstep * (n + 0.5) * k)
      if orthogonalize:
          cosmat[:,0] = cosmat[:,0] * 1./numpy.sqrt(2)
      return cosmat
docs: Return the orthogonal DCT-II/DCT-III matrix of size NxK.
      For computing or inverting MFCCs, N is the number of
      log-power-spectrum bins while K is the number of cepstra.