Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Each language has its own concepts. An important point of this language is to very often think of matrices as an array of vectors, each column an entry. Things will start to make sense then. If you don't want that behavior, use <code>matrix(:)</code> as the argument to those functions which will pass a single vector, rather than a matrix. For example:</p> <pre><code>octave&gt; a = magic (5); octave&gt; max (a) ans = 23 24 25 21 22 octave&gt; max (a(:)) ans = 25 </code></pre> <p>1) This is not true with at least Octave 3.6.4. I'm not 100% sure but may be related related to <a href="https://savannah.gnu.org/bugs/?37411" rel="nofollow">this bug</a> which has already been fixed.</p> <p>2) If you index with boolean values, it will considered to be a mask and treated as such. If you index with non-boolean values, then it's treated as the indexes for the values. This makes perfect sense to me.</p> <p>3) This is not true. The returned has always the same size of the index, independent if it's a matrix or vector. The only exception is that if the index is a vector, the output will be a single row. The idea is that indexing with a single vector/matrix returns something of the same size:</p> <pre><code>octave&gt; a = 4:7 a = 4 5 6 7 octave&gt; a([1 1]) ans = 4 4 octave&gt; a([1 3]) ans = 4 6 octave&gt; a([1 3; 3 1]) ans = 4 6 6 4 </code></pre> <p>4) <code>max</code> does take dimension as argument at least in Octave. From the 3.6.4 help text of <code>max</code>:</p> <blockquote> <p>For a vector argument, return the maximum value. For a matrix argument, return the maximum value from each column, as a row vector, or over the dimension DIM if defined, in which case Y should be set to the empty matrix (it's ignored otherwise).</p> </blockquote> <p>The rest applies like I said on the intro. If you supply a matrix, it will think of each column as a dataset.</p>
    singulars
    1. This table or related slice is empty.
    1. POOctave and Matlab "wat" matrix/vector inconsistencies
      singulars
      1. PTQuestion
    1. PTAnswer
    1. UScarandraug
    1. UScarandraug
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTDownMod
    1. COI don't think you understood what I was asking about. I was generally complaining that vectors aren't treated as matrices (whereas you seemed to think my problem was that matrices aren't treated as vectors) In case 2, I'm only indexing with booleans, never with numerics (not in either case), yet one returns a row vector and the other a column vector. In case 3, the exception you mention is exactly what I'm complaining about. If I have a matrix which I need to index with but the matrix has a variable number of columns, then I have to write an if statement for that one exception with only 1
      singulars
      1. PO
      1. USdspyz
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload