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Re: Help with octave syntax please.


From: Julien Martin
Subject: Re: Help with octave syntax please.
Date: Mon, 30 Aug 2010 20:21:58 +0200

thanks all for your replies,
J.

2010/8/30 John W. Eaton <address@hidden>
On 30-Aug-2010, Jordi Gutiérrez Hermoso wrote:

| On 30 August 2010 11:11, Julien Martin <address@hidden> wrote:
| > 1. I don't understand the bracket and the colon
| > [0:ds:Smax]
|
|      http://www.gnu.org/software/octave//doc/interpreter/Ranges.html#Ranges

Perhaps that section should also explain that if a range _expression_
appears inside square brackets it is converted to a matrix object,
which will then expand all the elements of the range and (almost
always) use up more memory.  For example:

 octave:1> x = 0:0.1:1;
 octave:2> y = [0:0.1:1];
 octave:3> whos
 Variables in the current scope:

   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  =====
        ans         1x30                        30  char
        x           1x11                        24  double
        y           1x11                        88  double

 Total is 52 elements using 142 bytes

 octave:4> typeinfo (x)
 ans = range
 octave:5> typeinfo (y)
 ans = matrix

jwe


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