# How to update all the weights in case only one data out of n signals is observable

If we have cost function as $$E_i = (D_i -Y_i)^T Q (D_i -Y_i)$$, where $$Q=\begin{bmatrix} 1 & 0 & 0\\ 0 & 0 & 0\\ 0 & 0 & 0 \end{bmatrix}$$( in case only one data signal can be measured) , only weights on the first row are updated.

Is there any way to update all weights? Or, is there any other cost function for this? if there is, could you let me know the reference or papers for it?