I have this code:

\begin{align*} \label{eq:svc2}
\stackrel{min}{\omega,b,\xi,\rho} \-\hspace{20pt} & \frac{1}{2}  \omega^T\omega - \nu \rho + \frac{1}{l} \sum_{i=1}^{l}{\xi_i} \\
\text{subject to} \-\hspace{20pt} & y_i(\omega^T\phi(x_i)+b) \geq \rho-\xi_i, \tag{eq:svc1}\\
& \xi_i \geq 0, i=1,...,l, \-\hspace{10pt} \rho \geq 0. \\

I want to add a label for the entire equation, not one for each line.

How may I do it? I have tried \label nexto to \begin{align*} but a get an [warning: reference xxx on page xx undefined on input line xx] when referencing it using \ref

  • 1
    By definition of the starred envs: they do not add equipment numbers, and btw: labels are to label some for later reference, it does not add the numbers. Replace align* by aligned, and wrap equation around that. This gives a single number plus alignment
    – daleif
    Mar 3, 2016 at 18:29

1 Answer 1


Perhaps you're thinking to aligned:


\min_{\omega,b,\xi,\rho} \qquad &
  \frac{1}{2}  \omega^T\omega - \nu \rho + \frac{1}{l} \sum_{i=1}^{l}\xi_i \\
\textup{subject to} \qquad &
  y_i(\omega^T\phi(x_i)+b) \geq \rho-\xi_i,\\
  & \xi_i \geq 0, i=1,\dots,l, \quad \rho \geq 0.


enter image description here

Note that \- makes no sense in math mode; also \min should be used and not \stackrel. For ... use \dots.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.