# How to write the following vector

I have written a vector

\begin{align}
\textbf{\underline w} &= \begin{bmatrix}
\textbf{0} \\
\textbf{v} \\
\textbf{0}
\end{bmatrix}
\end{align}


However I want to write the number of elements in the vector too. That is I want to write it like 0_{1\times 4} then v_{1\times 5} and so on.

Is it possible to write that in the vector w ?

How to do it?

• Although this is a personnal opition, I would not use such notations. Why would w be underlined and not v ? – BambOo Sep 1 '18 at 16:17
You should use \mathbf, not \textbf.
$$\underline{\mathbf{w}}= \begin{bmatrix} \mathbf{0}_{1\times 4}\\ \mathbf{v}_{1\times 5}\\ \mathbf{0}_{1\times 4} \end{bmatrix}$$