Is there an intelligent way to left-align the parts right of & of the two cases environments shown below (if x >= 0, otherwise, if y < 0, otherwise). I wonder if there is a better way than using manual spaces:
\begin{align*}
u(x) &=
\begin{cases}
0 & \text{if } x \geq 0 \\
1 & \text{otherwise}
\end{cases}
\\
\tau &=
\begin{cases}
a+b+c+d & \text{if } y < 0 \\
1 & \text{otherwise}
\end{cases}
\end{align*}
mathtools
package and use something like\mathrlap0\hphantom{a+b+c+d}
in place of your 0. But that's playing with manual spacing, I suppose. – TH. Sep 21 '10 at 2:04