# separate matrix equation

I want to separate my matric because its over the column size like patter below.

from
Vm(q,qdot) = [matrix]
to
Vm(q,qdot)
and not

$$\label{eq6} \begin{array}{c} V_m (\bf {q}, \bf{\dot {q}}) \end{array} \\ = \newline \left[ \begin{array}{cccccc} m_1 & 0 & 0 & 0 & 0 & 0 \\ 0 & m_2 & 0 & 0 & 0 & 0 \\ 0 & 0 & m_3 & 0 & 0 & 0 \\ 0 & 0 & 0 & 0 & I_z{\dot{\psi}} & -I_y{\dot{\theta}} \\ 0 & 0 & 0 & -I_z{\dot{\psi}} & 0 & J_t{\omega}+I_x\dot{\phi} \\ 0 & 0 & 0 & I_y{\dot{\theta}} & -J_t{\omega}-I_x\dot{\phi} & 0 \nonumber \end{array} \right]$$
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Welcome to TeX.sx! A tip: If you indent lines by 4 spaces, then they are marked as a code sample. You can also highlight the code and click the "code" button (with "{}" on it). To mark inline code you can use backticks (`). – Torbjørn T. Jun 29 '11 at 8:34

You're using quite old syntax (\bf in math mode, for example).

I suggest you to load the amsmath package, that gives many useful new environments for writing math efficiently.

A \newline is not allowed in a math display such as equation. With amsmath there is multline with its unnumbered variant multline*:

\begin{multline*}
V_{m}(\mathbf{q}, \dot{\mathbf{q}})=\\ % break here
\begin{bmatrix}
m_1 & 0 & 0 & 0 & 0 & 0 \\
0 & m_2 & 0 & 0 & 0 & 0 \\
0 & 0 & m_3 & 0 & 0 & 0 \\
0 & 0 & 0 & 0 & I_z\dot{\psi}  & -I_y\dot{\theta} \\
0 & 0 & 0 & -I_z\dot{\psi}  & 0 & J_t\omega+I_x\dot{\phi}   \\
0 & 0 & 0 & I_y\dot{\theta} & -J_t\omega-I_x\dot{\phi}   & 0
\end{bmatrix}
\end{multline*}
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