- 22nd June 2008, 16:27 #1
## matlab define matrix

How to define a matrix of variables in matlab?

For example I want a matrix like:

a=[sin(t) cos(t);cos(t) sin(t)]

so that "t" be a variable, when I assign t=.5 it should give to me

[0.4796 0.8776;0.8776 0.4796]

how should I do that?

help me if u can! thanks!

- 22nd June 2008, 16:27

- 22nd June 2008, 16:39 #2

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## matlab matrix variables

I don't quite understand your question. If I simply type your two statements into MATLAB:

t = .5

a = [sin(t) cos(t);cos(t) sin(t)]

it displays the resulting matrix as you requested:

0.479425538604203 0.877582561890373

0.877582561890373 0.479425538604203

Or do you want it formatted with square brackets and semicolon?

- 22nd June 2008, 17:21 #3
## matlab matrix with variables

No,

you should type the matrix definition first

I want to define a matrix (containing a variable such as "t")

then put it in a loop, and change the variable, and get different values

-----------

you should type: ( as I did! )

>> syms t

>> a=[sin(t) cos(t);cos(t) sin(t)]

a =

[ sin(t), cos(t)]

[ cos(t), sin(t)]

>> t=1.2;

>> a

a =

[ sin(t), cos(t)]

[ cos(t), sin(t)]

-----------------------------

is it clear?! I want "t" in the matrix to be a variable!

How can I do that?

thanks!

- 22nd June 2008, 18:31 #4

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## matlab variable matrix

Oh, that looks like Maple symbolic processing. Sorry, I've never explored that aspect of MATLAB.

- 19th July 2008, 14:24 #5

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## define variable in matlab

Code:syms t a=[sin(t) cos(t);cos(t) sin(t)] a=subs(a,t,0.1)

2 members found this post helpful.

- 19th July 2008, 14:24

- 3rd June 2011, 08:50 #6

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## Re: matlab define matrix

Hi ,

Is there any way to write a for loop in MATLAB to read the files i.e. texts that

are saved in a folder and do some operation on each in every iteration. So

let say if I have files 1.txt, 2.txt,,... all saved in a folder called

LOSS. i want to open 1.txt first----> do some calculation and display the

result, then open 2.txt and do the same calculation, then 3.txt and so on.

thanks

Anvari

- 11th July 2012, 10:06 #7

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## Re: matlab define matrix

a=[-0.5 0 0 0 ;1 -1 0 0;0 1 -3 0;0 0 1 -10];

k1=char;

k2=char;

k3=char;

k4=char;

s=char;

c=[k1 k2 k3 k4];

b=[4.5;1;0;0];

i=eye(4);

q=b*c;

t=s*i;

w=t-q;

e=det(w);

%++++++++++++++++++++++++++++++why this not true?

- 15th July 2013, 02:39 #8

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- 15th July 2013, 02:52 #9
## Re: define variable in matlab

1 members found this post helpful.

- 15th July 2013, 23:31 #10

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## Re: define variable in matlab

Is there a way in which I can resolve this.........?

Thanks for the help.

- 16th July 2013, 05:53 #11