">output</span>      <span class="string">[ D  x  E ]</span>
dMdm       <span class="string">output</span> <span class="string">mean</span> <span class="string">by</span> <span class="string">input</span> <span class="string">mean</span>                             <span class="string">[ E  x  D ]</span>
dSdm       <span class="string">output</span> <span class="string">covariance</span> <span class="string">by</span> <span class="string">input</span> <span class="string">mean</span>                       <