1 | initial version |

Alternatively, you can use collect():

```
sage: de.collect(ep)
ep^2*diff(f1(x), x, x) + ep*(diff(f0(x), x, x) + diff(f1(x), x)) + diff(f0(x), x)
```

To get the coefficient of ep^2 you can do:

```
sage: de.coefficients(ep)[2][0]
diff(f1(x), x, x)
```

To get all the coefficients at once:

```
sage: de.coefficients()
[[diff(f0(x), x), 0],
[diff(f0(x), x, x) + diff(f1(x), x), 1],
[diff(f1(x), x, x), 2]]
```

2 | No.2 Revision |

Alternatively, you can use collect():

```
sage: de.collect(ep)
ep^2*diff(f1(x), x, x) + ep*(diff(f0(x), x, x) + diff(f1(x), x)) + diff(f0(x), x)
```

To get the coefficient of ep^2 you can do:

```
sage: de.coefficients(ep)[2][0]
diff(f1(x), x, x)
```

To get all the coefficients at once:

```
sage: de.coefficients()
[[diff(f0(x), x), 0],
[diff(f0(x), x, x) + diff(f1(x), x), 1],
[diff(f1(x), x, x), 2]]
```

If you define

```
sage: epcoeff = [de.coefficients(ep)[i][0] for i in range(len(de.coefficients()))]
```

you can access the coefficient of `ep^n`

using `epcoeff[n]`

, so that you can feed it to `desolve`

etc.

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