Re: Manipulating a matrix
- To: mathgroup at smc.vnet.net
- Subject: [mg59266] Re: Manipulating a matrix
- From: "Dr. Wolfgang Hintze" <weh at snafu.de>
- Date: Thu, 4 Aug 2005 02:07:51 -0400 (EDT)
- References: <dcmuig$glg$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Wissam,
to begin with let's do it step by step in an example of a 3x3 matrix
In[17]:=
m = Table[i, {i, 1, 3}, {j, 1, 3}];
TableForm[m]
Out[18]//TableForm=
TableForm[{{1, 1, 1}, {2, 2, 2}, {3, 3, 3}}]
Drop the first row
In[19]:=
m1 = Drop[m, 1];
TableForm[m1]
Out[20]//TableForm=
TableForm[{{2, 2, 2}, {3, 3, 3}}]
Now drop the first column of the result sandwiching with Transpose
In[44]:=
m2 = Transpose[Drop[Transpose[m1], 1]];
TableForm[m2]
Out[45]//TableForm=
TableForm[{{2, 2}, {3, 3}}]
Ok. Now let's put the things together and define a function doing the
job in general ...
In[23]:=
mDrop[m_] := Transpose[Drop[Transpose[Drop[m, 1]], 1]]
... and test it
md = mDrop[m];
TableForm[md]
Out[26]//TableForm=
TableForm[{{2, 3}, {2, 3}}]
Regards,
Wolfgang
Ramier wrote:
> Hello everyone,
>
> I think that my question is rather simple and maybe I ought to go
> deeper into Mathematica book:
> I have a n x n matrix and I'd like to remove the first line and the
> first column in order to get the (n-1)x(n-1) matrix with the entries
> remaining. Is there a simple way to do that ?
>
> Perhaps my question is really simple or idiot but I've never used
> Mathematica before.
>
> Thanks a lot,
>
> Wissam
>
>