Search All of the Math Forum:

Views expressed in these public forums are not endorsed by NCTM or The Math Forum.

Topic: Iterative Procedure Using Vectors
Replies: 2   Last Post: Apr 26, 2013 3:26 AM

 Messages: [ Previous | Next ]
 Steven Lord Posts: 17,998 Registered: 12/7/04
Re: Iterative Procedure Using Vectors
Posted: Apr 25, 2013 2:30 PM

"Laura " <laurafilgate17@gmail.com> wrote in message
news:klbqnr\$mdk\$1@newscl01ah.mathworks.com...
> I have been told to carry out the following iterative procedure:
> a) Set a vector v to be the vector [1 ; 0]
> b) Find a new vector u = Av (where A is a 2 x 2 real matrix)
> c) Find the magnitude of this new vector u, and call this magnitude c
> d) Divide u by c
> e) Set v to be this unit vector, then repeat steps b) to e) a number of
> times.
>
> So far I have tried:
> v(1) = [1 ; 0]

You can't fit the two elements of [1; 0] into the one element of v(1). It's
too big. If you wanted to store that in the first column of v, that would
work:

v(:, 1) = [1; 0]

> for n = 1:100
> u(n) = A*v(n+1)

See above plus you'll want to change all your indexing to refer to columns
of the matrix rather than individual elements.

Also pay close attention to whether you want elementwise or vector division.
See:

http://www.mathworks.com/help/matlab/ref/rdivide.html
http://www.mathworks.com/help/matlab/ref/mrdivide.html

--
Steve Lord
slord@mathworks.com