How to | Get Parts of a Matrix

The Wolfram Language has many matrix operations that support operations such as building, computing, and visualizing matrices. It also has a rich language for picking out and extracting parts of matrices.

Define the following matrix. Note how a matrix in the Wolfram Language is not restricted to number entries:

Use Part to go to the first row and take the second element:

Or use the shorthand notation [[]] for Part:

To take an entire row, use one index to specify the row:

To take an entire column, you need to select all rows with All and specify the column:

    

To pick out a submatrix, you can use Span (;;). First, define a 4×5 matrix:

The top-left 3×4 matrix with bold entries here corresponds to rows 1 through 3 and columns 1 through 4:

Extract the highlighted matrix by using Span (;;) to specify the relevant span of rows and columns:

Extract all elements except the outermost rows and columns (negative indices count from the end):

  • Linear Algebra
  • Constructing Matrices
  • Typing Matrices
  • Entering Tables and Matrices
  • Vectors and Matrices
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  • Operations on Scalars, Vectors, and Matrices
  • How to: Get Elements of Lists
  • How to: Update Parts of a Matrix
  • How to: Do Linear Algebra
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  • How to: Perform Calculations on Columns of Data
  • Part  Span

  • Elements of Lists
  • Parts of Matrices
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