Re: Subscripting Matrices (Syntax Question ?)

• To: mathgroup at smc.vnet.net
• Subject: [mg14249] Re: Subscripting Matrices (Syntax Question ?)
• From: Harald Giese <giese at dkrz.de>
• Date: Mon, 12 Oct 1998 13:51:34 -0400
• Organization: Institut fuer Meereskunde, Universitaet Hamburg
• References: <6vf6bj\$djg@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```Arthur Chtcherba wrote:
> ...
> I am constructing a matrix (whose dimensions I do not know in advance),
> and later
> on I want to index various elements in the array.
>
> An index is in a form of a list, and want to use with a matrix but for
> example
>   mtx[[{1,3,2}]] = 0
> will not set element  mtx[1,3,2].
> ...

Hi Arthur,

mtx[[{1,3,2}]] = 0 does its job correctly:

In[2]:=
mtx=Range[5]
Out[2]=
{1,2,3,4,5}
In[3]:=
mtx[[{1,3,2}]] = 0
Out[3]=
0
In[4]:=
mtx
Out[4]=
{0,0,0,4,5}

However, "mtx[1,3,2]" is not the correct way of referencing matrix (i.e.
List-) elements in Mathematica. Instead type
{mtx[[1]], mtx[[3]], mtx[[2]]}
or
mtx[[{1,3,2}]]

Regards,
Harald

--
Harald Giese
Email: giese at dkrz.de
Phone: +49 (0)40 4123 5796; Fax: +49 (0)40 5605724 Institut fuer
Meereskunde der Universitaet Hamburg (Institute of Oceanography of the
University of Hamburg) Troplowitzstrasse 7, D-22529 Hamburg

```

• Prev by Date: Re: graphing implicit function
• Next by Date: Re: from Compositions to trees
• Previous by thread: Subscripting Matrices (Syntax Question ?)
• Next by thread: Re: Re: Outputting Strings to a file