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Topic: Vector definition using variables
Replies: 4   Last Post: Dec 7, 2012 6:55 AM

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Steven Lord

Posts: 17,944
Registered: 12/7/04
Re: Vector definition using variables
Posted: Dec 5, 2012 12:46 PM
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"Matt " <mathieu.horsky@gmail.com> wrote in message
news:k9nrj4$nrs$1@newscl01ah.mathworks.com...
> Hello guys,
>
> I am having the following problem when I want to use the following
> function :
>
> --------------
> tstep=0.1;
> final_time=30;
> vect1=0:tstep:final_time
> --------------
>
> So the vector produced should be 1x301 long. Now the problem is that my
> tstep value is defined like this :
>
> --------------
> tstep=((length(time)-1))/length(d)
> --------------
>
> Where time is a 1x301 vector so value for length(time) should be 301, and
> d is a 1x330 vector so the value for length(d) should be 330. Therefore
> the value for tstep should be (301-1)/330=0.909090
>
> When I put this above value manually into vect1, it gives me the correct
> vector that I am looking for, but I'm using the tstep value given by the
> calculation above (using the length function), it doesn't work. It gives
> me a 1x34 vector for example.


What do you expect the length of vect1 to be in this scenario? Seems to me
the tstep value for your second case is just over 9 times as large as the
step for your first case and the endpoints are the same, so the vector
should be approximately 1/9 the length. What is 301/9?

Did you intend for final_time to be related somehow to the values in the
time variable? That's not what you described.

--
Steve Lord
slord@mathworks.com
To contact Technical Support use the Contact Us link on
http://www.mathworks.com




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