Re: Noob ? about Transpose and List Operations
- To: mathgroup at smc.vnet.net
- Subject: [mg63704] Re: Noob ? about Transpose and List Operations
- From: Bill Rowe <readnewsciv at earthlink.net>
- Date: Tue, 10 Jan 2006 01:49:00 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
On 1/9/06 at 4:48 AM, tarahw at umich.edu (Tarah) wrote:
>In[61]:= B' = MatrixForm[Transpose[B]]
>and instead of getting the transpose, I get as output the same
>matrix B with two brackets and the word "Transpose" surrounding it.
> This is highly unhelpful ;-) What am I doing wrong?
Mathematica returns something unevaluated when it cannot determine the correct answer. Since Transpose is a built in function I am guessing you've not defined B, i.e., you did something like:
In[1]:=Transpose[b]
Out[1]=Transpose[b]
Contrast this with:
In[6]:=b = Table[10*i + j, {i, 3}, {j, 2}]
Out[6]={{11, 12}, {21, 22}, {31, 32}}
In[7]:=Transpose[b]
Out[7]={{11, 21, 31}, {12, 22, 32}}
A few other comments:
It is better practice to not define variables beginning with capital letters. Although this is valid syntax in Mathematica, there is always a potential conflict with built-in symbols that always start with capital letters. By using lower case, you are certain to avoid any conflict with built-in symbols.
Also, you almost certainly don't want b=MatrixForm[Transpose[...]]. This will give b the head MatrixForm, i.e., it will no longer be a matrix, i.e.,
In[12]:=
c=MatrixForm[Transpose[b]];
MatrixQ[c]
Out[13]=False
If you want to use MatrixForm for display purposes it would be better to do things as
MatrixForm[b=Transpose[...]]
Now b is a matrix and the display will be controlled by MatrixForm, i.e.,
In[14]:=
MatrixForm[c=Transpose[b]];
MatrixQ[c]
Out[15]=True
Even better would be to dispense with MatrixForm altogether and set the default output to TraditionalForm.
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