How can I get this graphic in Matlab?

The graph is: http://www.fileshare.ro/e29104168

Where:

"grade" means degrees

"suprareglaj" means override

The alfa axis is a logarithmic axis, and override axis is a decimal axis.

I also have a formula which I don't know how could it help. It is:

override=sqrt(1-psi^2)*abs(sec(alfa))*exp(-psi/sqrt(1-psi^2)*atan(-psi/sqrt(1-psi^2))∓alfa-pi)

Can somebody help me please?

Thanks in advance

[Azzi Abdelmalek]

What is X-coordinate?

[ionut]

alfa. It is an angle

[Walter Roberson]

Clicking "download now" for the image gets me to a dating site.

[Image Analyst]

Me too. Apparently ionut is in need of a Romanian dating partner. Regardless, he should post to someplace that shows us the image immediately and not have other roadblocks like having to download something or sign up for something.

[ionut]

What? Sorry for that. This was not my intention. I'll repair the error. Here is the graph:

http://imageshack.us/photo/my-images/716/39376496.jpg/

Sorry for all inconvenients

Answer 1

[Image Analyst]

Have you tried using semilogy() to do your plotting? It does a linear x axis and a log y axis. Or you can use semilogx() to do a linear y axis and a log x axis.

[ionut]

Yes, I tried but I can't get the graph. I really don't know how to make the connection between override alfa and psi to get the graph. I was thinking if I could obtain the graph step by step . I mean to obtain the graph for psi=0 than type "hold on" than for psi=0.1 and so on. Do you have any other idea?

Many thanks!:)

[Image Analyst]

Can you supply some data for us to use? Would that data be a family of curves like the image you posted?

[ionut]

Well yes. I have an example which says:

For example if override is 10% I'll obtain the next pairs:

psi1=0.8 & alfa1=40°; psi2=0.7 & alfa2=20°; psi3=0.6 & alfa3= -20°

Hope to be helpful. I would give to you the document but is written in romanian.

[Image Analyst]

psi(1)=0.8;
alfa(1)=40;
psi(2)=0.7;
alfa(2)=20;
psi(3)=0.6;
alfa(3)= -20;
alfa = alfa * pi/180; % Convert to radians
override=sqrt(1-psi.^2).*abs(sec(alfa)).*exp(-psi./sqrt(1-psi.^2).*atan(-psi./sqrt(1-psi.^2)))

In the command window:

override =
          2.69684640284932          1.62510389629997          1.37944981741136

[ionut]

Thank you very much for your help. It seems to be ok, but I don't know why doesn't work. I mean I don't know what should I do to get at least a part of graph. I've seen that you changed the last part of my formula. Why did you do that?

[Image Analyst]

plus or minus some number (alfa-pi) is not correct MATLAB syntax. If you want to, you can have a loop over various values of alfa and build a 2D array of override, or whatever you want to do.

[ionut]

Understood. You're right. I'll try to see how to manage those values to get that damn graph.:D:))). If you get another idea please let me know it.

Many thanks again.

[Image Analyst]

Not that I can think of without digging into it further to really understand what you want. I'd be happy to look over your final code, but if we're done, then go ahead and mark it as "Answered".

[ionut]

Be sure that I'll give you the final code, when I'll be done. The deadline for my project is 23.01.2013, sa till then you'll have the code. I know that's very hard to explain 'cause this graph is part of a project.

Well I'll exaplain you in general the problem: I have H(s)=5/(5*s+1)(2*s+1). From this I must design a digital regulator whith the allocation pole-zero method for numerical control loop to ensure zero stationary error at step input; where override imposed is 10% and maximum duration of transitory regime is tr_imposed=6.5 sec.. tr=4/(psi*0.769).

I don't know if you really understand because my technical english is not so good