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From: Rob Campbell on 17 Jun 2010 12:30

> Wait, so what is the exact difference between { and [? I always used [ thinking I would
>be making a matrix.

Yes, you're basically right but look in the Matlab programming docs for details. The catch is that the [ ] operator means "do concatenation" not "make matrix". So you could do t=[1,10,33] or t=[1,2,3]. But note that you can also do t=1:3, where you're making vector without the square brackets because nothing is being concatenated.

The { } means "construct cell array." I think of a cell array as an array of pointers to anonymous variables. A cell array isn't a matrix because you can do things like:
t={'A', ones(10), 'lskdfhjlkds'}
This is why it's possibly more suitable for what you want--each string can be a different length and they can't interact with each other.
From: Yukiko Shimizu on 17 Jun 2010 12:49
Alright, thank you very much. Could you also explain what this means:

??? Output argument "qa" (and maybe others) not
assigned during call to "H:\dcm2quat.m>dcm2quat".

my input output function is:

function [qa,qb]=dcm2quat(A,type)

and I'm trying to just output qb since qa is not applicable in this case.

"Yukiko Shimizu" <yk.mizu(a)gmail.com> wrote in message <hvdgik$eoo$1(a)fred.mathworks.com>...
> Hello.
>
> Say I have type='xyz'
> and C=['xyz' 'xxy 'zyx']
> How do I check if type is an element of C? If it is I want it to return a logical 1.
>
> Thank you.
From: Yukiko Shimizu on 17 Jun 2010 13:28
NM, Thank you all very much for your help.

"Yukiko Shimizu" <yk.mizu(a)gmail.com> wrote in message <hvdjm2$3c3$1(a)fred.mathworks.com>...
> Alright, thank you very much. Could you also explain what this means:
>
> ??? Output argument "qa" (and maybe others) not
> assigned during call to "H:\dcm2quat.m>dcm2quat".
>
> my input output function is:
>
> function [qa,qb]=dcm2quat(A,type)
>
> and I'm trying to just output qb since qa is not applicable in this case.
>
> "Yukiko Shimizu" <yk.mizu(a)gmail.com> wrote in message <hvdgik$eoo$1(a)fred.mathworks.com>...
> > Hello.
> >
> > Say I have type='xyz'
> > and C=['xyz' 'xxy 'zyx']
> > How do I check if type is an element of C? If it is I want it to return a logical 1.
> >
> > Thank you.
From: Rob Campbell on 17 Jun 2010 14:08

> ??? Output argument "qa" (and maybe others) not
> assigned during call to "H:\dcm2quat.m>dcm2quat".
>
> my input output function is:
>
> function [qa,qb]=dcm2quat(A,type)
>
> and I'm trying to just output qb since qa is not applicable in this case.

It's not working because qa isn't being defined. You can do various things.
One is to define qa and qb as empty variables (qa=[ ]; qb= [ ]) right at the start of dcm2quat. That way you always get both outputs even though you may not use them.

Another thing you could do is to package all outputs of the function as a structure. e.g.
function out=dcm2quat(A,type)
out.qb='something'
end
That way it won't matter that qa wasn't defined and it's easy to add more variables.

As a side note, you shouldn't call the variable "type". This is because there's already a function called "type" (see help type). Your variable names take priority over function names and so you can mask a function when you define variable with the same name. e.g.
>> rand(1,3)
ans =
0.8147 0.9058 0.1270

>> rand=[ ];
>> rand(1,3)
??? Index exceeds matrix dimensions.
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