# Question in MATLAB

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• December 26th 2011, 11:42 PM
nezar
Question in MATLAB
[IMG]http://img823.imageshack.us/img823/2572/42582392.png [/IMG]
• December 27th 2011, 05:26 AM
Ackbeet
Re: Question in MATLAB
Quote:

Originally Posted by nezar
[IMG]http://img823.imageshack.us/img823/2572/42582392.png [/IMG]

What ideas have you had so far?
• December 27th 2011, 06:32 AM
nezar
Re: Question in MATLAB
actually no
• December 27th 2011, 07:05 AM
Ackbeet
Re: Question in MATLAB
I would probably start by defining a vector that contains the $R_{L}$ values. How could you do that?
• December 27th 2011, 08:36 AM
CaptainBlack
Re: Question in MATLAB
Quote:

Originally Posted by nezar
actually no

Why not this is not the first Matlab plot question you have asked?

In fact I see no reason why you should have a problem with this since you have code to plot the other one.

CB
• December 27th 2011, 09:05 AM
nezar
Re: Question in MATLAB
i am sorry i am really try to get the answer ,but i don't get any thing
rl=(1,10,1000);
p=12^2.*rl/(rl+2.5)^2;
plot(p);
• December 27th 2011, 09:45 AM
Ackbeet
Re: Question in MATLAB
Quote:

Originally Posted by nezar
i am sorry i am really try to get the answer ,but i don't get any thing
rl=(1,10,1000);
p=12^2.*rl/(rl+2.5)^2;
plot(p);

I would modify your last line. What your current last line will do is plot p as a function of the index. But you really want to plot as a function of rl. Hence, I would do this:

plot(rl,p)

See what that does.
• December 27th 2011, 09:51 AM
CaptainBlack
Re: Question in MATLAB
Quote:

Originally Posted by nezar
i am sorry i am really try to get the answer ,but i don't get any thing
rl=(1,10,1000);
p=12^2.*rl/(rl+2.5)^2;
plot(p);

Have you tried typing any of this at the command line?

CB
• December 27th 2011, 10:15 AM
nezar
Re: Question in MATLAB
Quote:

Originally Posted by Ackbeet
I would modify your last line. What your current last line will do is plot p as a function of the index. But you really want to plot as a function of rl. Hence, I would do this:

plot(rl,p)

See what that does.

i try but he gave me
??? Error: File: nezarn.m Line: 1 Column: 6
Expression or statement is incorrect--possibly unbalanced (, {, or [.
• December 27th 2011, 10:50 AM
Ackbeet
Re: Question in MATLAB
Quote:

Originally Posted by nezar
i try but he gave me
??? Error: File: nezarn.m Line: 1 Column: 6
Expression or statement is incorrect--possibly unbalanced (, {, or [.

I suspect your first line is not the correct syntax for defining a vector in MATLAB. You're after, apparently, a vector containing 1000 numbers ranging from 1 to 10. Try this expression instead:

rl=1:0.009:10;
• December 27th 2011, 10:55 AM
nezar
Re: Question in MATLAB
Quote:

Originally Posted by CaptainBlack
Have you tried typing any of this at the command line?

CB

no
• December 27th 2011, 11:11 AM
nezar
Re: Question in MATLAB
Quote:

Originally Posted by Ackbeet
I suspect your first line is not the correct syntax for defining a vector in MATLAB. You're after, apparently, a vector containing 1000 numbers ranging from 1 to 10. Try this expression instead:

rl=1:0.009:10;

error
??? Error using ==> mpower
Matrix must be square.

Error in ==> nezarn at 2
p=12^2.*rl/(rl+2.5)^2;
• December 27th 2011, 11:13 AM
Ackbeet
Re: Question in MATLAB
Quote:

Originally Posted by nezar
error
??? Error using ==> mpower
Matrix must be square.

Error in ==> nezarn at 2
p=12^2.*rl/(rl+2.5)^2;

Try using dots everywhere, since you're wanting component-wise arithmetic. That is, try

p=12^2.*rl./(rl+2.5).^2;

Note: you actually don't need a dot for the first one, because that's a scalar. So you could probably do

p=12^2*rl./(rl+2.5).^2;
• December 27th 2011, 11:41 AM
nezar
Re: Question in MATLAB
Quote:

Originally Posted by Ackbeet
Try using dots everywhere, since you're wanting component-wise arithmetic. That is, try

p=12^2.*rl./(rl+2.5).^2;

Note: you actually don't need a dot for the first one, because that's a scalar. So you could probably do

p=12^2*rl./(rl+2.5).^2;

thank you for help me
• December 27th 2011, 11:43 AM
Ackbeet
Re: Question in MATLAB
Quote:

Originally Posted by nezar