Latex长公式的换行可以用split或者aliged，在要换行的地方用\\。例：
begin{equation}
begin{split}
mu_pi(k) = mu_v(k)otimes_g[mu_t(k)otimes_t...mu_t(k+H_p-1)]
otimes_{c1}[mu_s(k)otimes_s...mu_s(k+H_p-1)]
otimes_{c2}[mu_p(k)otimes_p...mu_p(k+H_p-1)]
end{split}
end{equation}
上面例子的公式是右对齐的，如果要左对齐就在每行的开头加&。
begin{equation}
begin{split}
& mu_pi(k) = mu_v(k)otimes_g[mu_t(k)otimes_t...mu_t(k+H_p-1)]
& otimes_{c1}[mu_s(k)otimes_s...mu_s(k+H_p-1)]
& otimes_{c2}[mu_p(k)otimes_p...mu_p(k+H_p-1)]
end{split}
end{equation}