1 | initial version |

The error " list index out of range" means you are trying to index a list beyond it's boundary.

In the code:

```
for i in (1,4):
phi[i][0]=1
```

you are iterating over the tuple `(1,4)`

, this means `i`

will take the values 1 and 4 in the loop. Perhaps you want to replace `(1,4)`

by `range(1,4)`

like you have in loops above. This will cause `i`

to take the values `1,2,3`

.

Another comment, probably unrelated to your error, in the definition:

```
It = lambda f: integral(f,t,0,t)
```

represents a very common Calculus I student error. You are trying to use `t`

as both the integration variable and the limit of integration. This does not make sense mathematically. If you want the resulting function to be a function of `t`

(the variable that you want to assume is > 0), use a dummy variable in your integration, e.g.

```
var('s')
It = lambda f: integral(f(s),s,0,t)
```

2 | No.2 Revision |

The error " list index out of range" means you are trying to index a list beyond ~~it's ~~its boundary.

In the code:

```
for i in (1,4):
phi[i][0]=1
```

you are iterating over the tuple `(1,4)`

, this means `i`

will take the values 1 and 4 in the loop. Perhaps you want to replace `(1,4)`

by `range(1,4)`

like you have in loops above. This will cause `i`

to take the values `1,2,3`

.

Another comment, probably unrelated to your error, in the definition:

```
It = lambda f: integral(f,t,0,t)
```

represents a very common Calculus I student error. You are trying to use `t`

as both the integration variable and the limit of integration. This does not make sense mathematically. If you want the resulting function to be a function of `t`

(the variable that you want to assume is > 0), use a dummy variable in your integration, e.g.

```
var('s')
It = lambda f: integral(f(s),s,0,t)
```

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