How to | Get Elements of Lists
Lists are very important structures in Mathematica. Lists allow you to treat any kind of collection of objects as a single entity. Sometimes you need to pick out or extract individual elements or groups of elements from a list.
Set up a list of the first 10 squares (stored as 
):
| Out[256]= |  |
Use Part to pick the third element of the list:
| Out[257]= |  |
Or use 
(the short form notation for Part):
| Out[258]= |  |
Combine 
(the short form for Span) with Part to pick out the elements from 1 to 5:
| Out[259]= |  |
Pick out elements 5 through 8 of the list:
| Out[260]= |  |
Pick the last 7 elements (negative indices count from the end):
| Out[261]= |  |
A matrix in Mathematica is a list of lists of the same length. You can pick out elements from a matrix just like you would from a list.
Set up a 5×5 matrix of integers:
| Out[262]= |  |
Use MatrixForm to see it laid out as a matrix:
Out[263]//MatrixForm= |
| |  |
The first part of the matrix is the first row:
| Out[264]= |  |
