How to define a column vector whose elements are column vector?

I want to define a matrix like d=[ [1;2;3] ; [4;5;6] ; [7;8;9] ] such that d(1) gives a 3X1 matrix [1;2;3], but instead I am getting d matrix as 9X1 as d(1)=1. How can I represent my d matrix in the form given above?

Answer 1

[Guillaume]

You have to use a cell array:

d = {[1;2;3]; [4;5;6]; [7;8;9]};  
d{1}  %to get the first vector

[Deepak Patankar]

Thanks Sir

Actually I am using ssest(data(as iddata),nx) to find the estimated parameters for my state space model.

x[t+Ts]=Ax[t] + Bu[t]

y[t] = C*x[t]

where u[t] is a nX3 matrix( n is number of sample) and y[t] is n*1 matrix.

Since u[t] is nX3 the output y[t] comes 1X3, but to get the best estimate y[t] must be 1X1 ( I tried taking y as [output,0,0] and few more combinations it was not giving good result). Thus to take y as 1X1 my u must be 3X1, that's why I asked the question which you answered earlier.But I am unable to use cell array in iddata. Can you suggest some solution for the actual problem ?

[Guillaume]

I know nothing about state space model and I don't really understand your problem.

In any case, since it's so vastly different to the question you've asked here, start a new question. You'll be a lot more likely to get an answer. Be a lot clearer in your new question.

Answer 2

[David Goodmanson]

Hello Deepak,

If you want to create an actual matrix that you could access with a slightly different syntax, then

% commas concatenate horizontally, semicolons concatenate vertically
d=[ [1;2;3] , [4;5;6] , [7;8;9] ]

and then the columns would be addressed as d(:,1) = [1;2;3] etc.

[Deepak Patankar]

Thanks a lot sir for your answer

The question I asked was a small part of my actual problem which I have mentioned in Guillaume Sir's answer. Can you help me with the actual problem,I am trying it from quite a few days ?