O'Reilly logo

GNU Octave by Jesper Schmidt Hansen

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Time for action – manipulating arrays

  1. To delete the second column in A, we use:
    octave:14> A(:,2) = []
    
    A =
      1   3
      1   3
    
  2. We can extend an existing array, for example:
    octave:15 > b = [b 4 5]
    
    b =
      1 2 3 4 5
    
  3. Finally, try the following commands:
    octave:16> d = [2 4 6 8 10 12 14 16 18 20]
    
    d =
      2    4    6    8    10    12    14    16    18    20
    
    octave:17> d(1:2:9)
    
    ans =
      2    6    10   14    18
    
    octave:18>  d(3:3:12) = -1
    
    d =
      2    4    -1    8    10    -1    14    16    -1    20    0    -1
    

What just happened?

In Command 14, Octave interprets [] as an empty column vector and column 2 in A is then deleted in the command. Instead of deleting a column, we could have deleted a row, for example as an empty column vector and column 2 in A is then deleted in the command.

octave:14> A(2,:)=[]

On the right-hand side of the equal ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required