General ⇒ Problem with \left

[RedFox2010]

This is the code :

Code: Select all

\begin{equation}
	\left\{ \begin{array}{l} B(t) = 	F(t,A(t),J(t)) + \int_{0}^{t} K(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma, \\ 
	A(t) = 	G_A(t,A(t),J(t)) + \int_{0}^{t} H_A(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma\\ 
	J(t) = 	G_J(t,A(t),J(t)) + \int_{0}^{t} H_J(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma\\ 
	\end{array}
	\right.
	\label{cap3_eq1}
\end{equation}\\

This is the error :



where the prb is? Someone can help me?
tnx

[gmedina]

Hi,

I didn't get any problems compiling your code. Perhaps you didn't load the amsmath package? (For some reason (my browser maybe?) I couldn't see the error that you included). Below I post a complete compilable example using your code and a modified version using the cases environment provided by amsmath, and with some suggested variations:

Code: Select all

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation}
   \left\{ \begin{array}{l} B(t) =    F(t,A(t),J(t)) + \int_{0}^{t} K(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma,\\
   A(t) =    G_A(t,A(t),J(t)) + \int_{0}^{t} H_A(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma\\
   J(t) =    G_J(t,A(t),J(t)) + \int_{0}^{t} H_J(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma\\
   \end{array}
   \right.
   \label{cap3_eq1}
\end{equation}

\begin{equation}
\begin{cases}
   B(t) &=    F(t,A(t),J(t)) + \displaystyle\int_{0}^{t} K(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma,\\[.7em]
   A(t) &=    G_A(t,A(t),J(t)) + \displaystyle\int_{0}^{t} H_A(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma,\\[.7em]
   J(t) &=    G_J(t,A(t),J(t)) + \displaystyle\int_{0}^{t} H_J(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma.
\end{cases}
\end{equation}

\end{document}

[Juanjo]

I can't reproduce too the errors only with the provided code. Anyway, the \\ command after \end{equation} is completely superfluous and yields a warning (Underfull \hbox...). In addtition to the alternatives given by gmedina, you can try the following one:

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\begin{equation}
  \left\{
  \begin{aligned}
    B(t) &= F(t,A(t),J(t)) + \int_{0}^{t} K(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma,\\
    A(t) &= G_A(t,A(t),J(t)) +\int_{0}^{t} H_A(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma,\\
    J(t) &= G_J(t,A(t),J(t)) +\int_{0}^{t} H_J(t,t-\sigma,A(t),J(t))B(\sigma)d\sigma.
  \end{aligned}
  \right.
\end{equation}

The advantage of the aligned environment over array or cases is that each line is typeset in display mode, avoiding the need of \displaymath and any eventual optional argument of \\.