Getting an element of a sequence or a list

### 6.1.6 Getting an element of a sequence or a list

The elements of a sequence have indices beginning at 0 in Xcas mode and 1 in other modes (see Section 2.5.2).

You can get the an element of index n of a sequence or list by following the sequence or list with [n] (see Section 3.2.4).

(Note that head(S) does the same thing as S[0].)

#### Examples

(0,3,2)[1]

3 |  |  |  |  |  |  |  |  |  |

S:=2,3,4,5:; S[2]

4 |  |  |  |  |  |  |  |  |  |

[A,B,C,D][2]

C |  |  |  |  |  |  |  |  |  |

For lists, the at command can also be used to get the element at a specific position.

- at takes two arguments:
  - L, a list.
  - n, an integer.
- at(L,n) returns the element of S with index n.

##### Note.

at cannot be used for sequences, since the second argument would be merged with the sequence.

#### Example

[0,1,2][1]

or:

at([0,1,2],1)

1 |  |  |  |  |  |  |  |  |  |