dct_mat_2 = np.zeros((65536,65536))

N = dct_mat.shape[1]

n_v = np.arange(0,65536)


for m in tqdm(range(dct_mat.shape[0])):
    if m == 0:
        au = np.sqrt(1/N)
    else:
        au = np.sqrt(2/N)
    dct_mat_2[m,:] = au*np.cos(((2*n_v+1)*m*np.pi)/(2*N))