Insert a typeset matrix.
By Typing...
Type a matrix using nested curly braces:
Use MatrixForm to format a matrix as a 2D array:
In[2]:=2
✖
Out[2]=2
Using the Menu...
Choose Insert ▶ Table/Matrix ▶ New..., select Matrix, enter the numbers of rows and columns and click OK. Use 
to move through successive matrix positions, filling in values:
Programmatically...
Create a matrix with any function that returns a list of equal-sized lists, for example, Table:
In[3]:=3
✖
Out[3]=3
- Many functions are available for creating special types of matrices, for example, DiagonalMatrix, ConstantArray and HilbertMatrix.