MATLAB Central Newsreader - matlab code doesnt work

Re: matlab code doesnt work

Jos — Tue, 18 Dec 2007 22:00:09 -0500

kaancho <kaancho12@hotmail.com> wrote in message
<10642267.1198014032538.JavaMail.jakarta@nitrogen.mathforum.
org>...
> thanks for all the replies. The code indeed works. For
some reason when i had to close matlab and restart it to
take the data properly...maybe like Roger said I need to
initialize the array.

You should not need to close matlab. Issueing a "clear ret"
or even better (!) pre-allocate ret to it's final size
(i.e., initializing) should do.

The error you get is similar to

a = ones(3,2) ;
a(1,:) = 1:10 ;

Jos

Re: matlab code doesnt work

kaancho — Tue, 18 Dec 2007 21:40:02 -0500

thanks for all the replies. The code indeed works. For some reason when i had to close matlab and restart it to take the data properly...maybe like Roger said I need to initialize the array.

Re: matlab code doesnt work

Roger Stafford — Sun, 16 Dec 2007 06:38:49 -0500

kaancho12 <kaancho12@hotmail.com> wrote in message
<11132067.1197780702950.JavaMail.jakarta@nitrogen.mathforum.org>...
> Hi,
> I am trying to implement this code (which was on a lecture slide that I
found on the internet) but I could not figure out the error code. Any help is
appreciated:
> price = [74.9 108.34 82.52 47.2 10 8;
> 78.85 108.9 82.7 47.34 11 6;
> 79.86 118 83.3 49.44 12 9;
> 88.53 120.05 81.75 48.23 11 9;
> 88.84 134.31 81.13 49.25 12 8
> ];
>
>
> [n,col] = size(price);
> for i=2:n
> ret(i,:) = (price(i,:)-price(i-1,:))./price(i-1,:);
> end
>
> The error I get is:
> ??? Error using ==> run
> Subscripted assignment dimension mismatch.
>
> Any idea how to modify my subscript to make this work?
-------
In all likelihood, you are running this, having already created a 'ret' array of
a different size from the above 5 by 6, and matlab complains about the
mismatch in size that it sees.

In any case you should always preallocate to the proper size such arrays that
are to be filled up step-by-step in a for-loop so that their memory can be set
aside ahead of time rather than being expanded in a series of steps. That will
improve execution time.

Roger Stafford

Re: matlab code doesnt work

John O'Flaherty — Sun, 16 Dec 2007 05:32:19 -0500

On Sat, 15 Dec 2007 23:50:41 EST, kaancho12 <kaancho12@hotmail.com>
wrote:

>Hi,
>I am trying to implement this code (which was on a lecture slide that I found on the internet) but I could not figure out the error code. Any help is appreciated:
>price = [74.9 108.34 82.52 47.2 10 8;
>78.85 108.9 82.7 47.34 11 6;
>79.86 118 83.3 49.44 12 9;
>88.53 120.05 81.75 48.23 11 9;
>88.84 134.31 81.13 49.25 12 8
>];
>
>
>[n,col] = size(price);
>for i=2:n
>ret(i,:) = (price(i,:)-price(i-1,:))./price(i-1,:);
>end
>
>The error I get is:
>??? Error using ==> run
>Subscripted assignment dimension mismatch.
>
>Any idea how to modify my subscript to make this work?

It seems to work here- this is the result:
ret = 0 0 0 0 0 0
    0.0527 0.0052 0.0022 0.0030 0.1000 -0.2500
    0.0128 0.0836 0.0073 0.0444 0.0909 0.5000
    0.1086 0.0174 -0.0186 -0.0245 -0.0833 0
    0.0035 0.1188 -0.0076 0.0211 0.0909 -0.1111

Maybe there's a difference between what you pasted in the message and
what you're running.
--
John

matlab code doesnt work

kaancho12 — Sun, 16 Dec 2007 04:50:41 -0500

Hi,
I am trying to implement this code (which was on a lecture slide that I found on the internet) but I could not figure out the error code. Any help is appreciated:
price = [74.9 108.34 82.52 47.2 10 8;
78.85 108.9 82.7 47.34 11 6;
79.86 118 83.3 49.44 12 9;
88.53 120.05 81.75 48.23 11 9;
88.84 134.31 81.13 49.25 12 8
];

[n,col] = size(price);
for i=2:n
ret(i,:) = (price(i,:)-price(i-1,:))./price(i-1,:);
end

The error I get is:
??? Error using ==> run
Subscripted assignment dimension mismatch.

Any idea how to modify my subscript to make this work?