File Exchange Pick of the Week

September 6th, 2007

MATLAB Basics video: Absolute and Logical indexing

This is one in a series of videos covering MATLAB basics. It is meant for the new MATLAB user.

This video covers how to use row and column notation to be able to pull a subset of data from a larger matrix. This is a basic skill that is required for anyone that is going to use MATLAB. This particular type of indexing is less intuitive than the mat(row,col) indexing, it deals with using a single value as an index into a matrix like mat(ind) and mat([0 1 0 0 1]). These are also very important techniques for indexing into MATLAB.

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By Doug Hull

12:13 UTC | Posted in MATLAB Basics, Video | Permalink |

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3 Responses to “MATLAB Basics video: Absolute and Logical indexing”

  1. naor replied on September 6th, 2007 at 17:51 UTC :

    Doug, in the RSS feed of your blog, read in internet explorer 7, the videos never show. I don’t mean they don’t run, there are just lines of text with a single blank line where the videos should be. Is there a way to fix this?
    Thanks,
    naor (win32xp r2006a)

  2. Dennis Olly replied on March 1st, 2008 at 19:12 UTC :

    Hi Doug, very clear video, however, is it possible to do logical indexing directly to a submatrix, eg:

    data=zeros(10,10,10);

    here data(:,:,5) could be slice.
    now let

    mask=zeros(10,10);mask(5:5,8:8)=1;

    Is it possible to use this mask to logically index the submatrix data(:,:,5)?

    slice = data(:,:,5);
    and then accessing slice(mask) is possible. But can this not be done directly, without extracting ’slice’?

    Thanks
    Dennis

  3. Doug replied on March 3rd, 2008 at 14:20 UTC :

    It will be required to pull out the intermediate values to use that logical matrix or you will need to do some other indexing method.

    Doug

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