I have the following equations with-in alignat environment

```
$\begin{alignat}{4}
&p^0\colon\od{u_0(x)}{x} = 0 \quad &\text{with} \quad u_0(0) = 1, \\
&p^1\colon \od{u_1(x)}{x} -u_{{0}} \left( x \right) =0 \quad &\text{with} \quad u_1(0) = 0, \\
&p^2\colon \od{u_2(x)}{x} -u_{{1}} \left( x \right) =0 \quad &\text{with} \quad u_2(0) = 0, \\
&p^3\colon \od{u_3(x)}{x} -u_{{2}} \left( x \right) =0 \quad &\text{with} \quad u_3(0) = 0. \\
\end{alignat}$
```

In my document these equations are numbered as (1), (2), (3) and so-on.

How can I number these equations as (1.1), (1.2), (1.3) without affecting other equations that will come after these equaitons?

Thank you for helping me.

## Best Answer

You want to use the

`subequations`

environment, as follows:which produces the following output: