MATLAB Central Newsreader - reshape problem

reshape problem

Marcel — Sat, 02 Feb 2008 21:27:02 -0500

Hi i have this script
I want to reshape matrix A to matrix C with different number
of collums and rows

A=[1 1 1 1 1;2 2 2 2 2;3 3 3 3 3 ;4 4 4 4 4 ;5 5 5 5 5];
C=[];
[m,n]=size(A);
p=m*n;
if p/8==0
     d=p/8;
     C=reshape(A,8,d)
else
     for i=1:7
        while p/8==0

            p=m*(n+i);
            d=p/8;
           C=reshape(A,d,8)
         end

         end

     end

end

but there is an error..

??? Undefined function or variable 'C'.

Error in ==> C:\MATLAB6p5\work\TEST.m

where is the problem?
please let me know.
Thanks

Re: reshape problem

Nasser Abbasi — Sat, 02 Feb 2008 21:50:07 -0500

"Marcel " <JMarcel2@gmail.com> wrote in message
news:fo2n76$rk$1@fred.mathworks.com...
> Hi i have this script
> I want to reshape matrix A to matrix C with different number
> of collums and rows
>
> A=[1 1 1 1 1;2 2 2 2 2;3 3 3 3 3 ;4 4 4 4 4 ;5 5 5 5 5];
> C=[];
> [m,n]=size(A);
> p=m*n;
> if p/8==0
> d=p/8;
> C=reshape(A,8,d)
> else
> for i=1:7
> while p/8==0
>
> p=m*(n+i);
> d=p/8;
> C=reshape(A,d,8)
> end
>
> end
>
> end
>
> end
>
> but there is an error..
>
> ??? Undefined function or variable 'C'.
>
> Error in ==> C:\MATLAB6p5\work\TEST.m
>
> where is the problem?
> please let me know.
> Thanks
>
>

hello;

That is a little strange code you have there. I am not sure I understand it.

You say that if p/8 is zero then do something else you enter into some loop
which runs while p/8 is zero?? How are you going to have that while be true
if you are there because it is not true in the first place? there is nothing
there which would change that test.

(ps. you also seem to have an extra end hanging at the end)
(pps. it is not a good idea to check for equality between floating points
numbers using ==, help eps)

Nasser

reshape problem

Roger Stafford — Sat, 02 Feb 2008 22:02:01 -0500

"Marcel " <JMarcel2@gmail.com> wrote in message <fo2n76$rk
$1@fred.mathworks.com>...
> Hi i have this script
> I want to reshape matrix A to matrix C with different number
> of collums and rows
>
> A=[1 1 1 1 1;2 2 2 2 2;3 3 3 3 3 ;4 4 4 4 4 ;5 5 5 5 5];
> C=[];
> [m,n]=size(A);
> p=m*n;
> if p/8==0
> d=p/8;
> C=reshape(A,8,d)
> else
> for i=1:7
> while p/8==0
>
> p=m*(n+i);
> d=p/8;
> C=reshape(A,d,8)
> end
>
> end
>
> end
>
> end
>
> but there is an error..
>
> ??? Undefined function or variable 'C'.
>
> Error in ==> C:\MATLAB6p5\work\TEST.m
>
> where is the problem?
> please let me know.
> Thanks
--------
The quantity p/8 (= 25/8) is not zero, so in the 'else' part the 'while' loop
never gets started in any of the seven trips through the 'for' loop.

Roger Stafford