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Could someone explain me what I must change in my model?
Model
The error messages are pretty clear and self-explanatory. The reason you get the error is because B is of dimension 4x2 and you are trying to do B * Xr where Xr is of dimension 1. According to your equation, you need to do B*U where U = [dXr/dt; Xr];. However, using the derivative block is never a good idea in Simulink if you can avoid it, especially with a step input. Think about how you want to formulate the inputs to your state-space.
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syms k
S1 = symsum(1/((2*k)+1)^2,k,0,1000)
The result is this
59039372973827482202940226722672826425297321906316082356858983822169051832268260251807527611479190413293513875429587706186073872918905490907386679472102966658686481651660967093301512141946288248492833396616338323741632085379508599235923841007033467883638349122388806376761808189104503262045883240287482992169819848342303098664924237976221795758421152603069387903705445513260596627332283139648508194960733619500093010571517561429904500013876585156927070119332440687162376758374919870699278800835146651318465663183182583101377584105366558079836223068786457324044080570317649838092783113721959819118571747662368360095513856052974454509201490370810246175872510881504730747209788019551000695511879992198550955686739483474761130248789609061549535677663474218135370195381615899214931316241080337028498241295985409686314819267606796712968280842464845294917738460317179001491697993067157425958639996885239616893392960282441289069600101430806922004624472226999315951355963789249300352610312601262349650287009275097201871774652260892220551489305368617001974326978428202443548923140478853569492070442010110016068635424791389124439271253578545895132216218268847919848655110002938693346760862649668457282775860633067627110099340660770861888592018701206483696615682617062811616008107086256694453990688805738127607846586853460003073465075155412119309273843527076321601670400373937698518621100907936577387919537592519265365346619712200304996044229704602647674114176291753575322917531444831938509001759491229575945273985556769609288625450013634760596805884195325794441020339210402987018058377081579351119704065092777310976461961832919116412535470810011337916688085616171422473409544885864650134157327448050685723673514545806331081542320899927
It is a number in this form a/b
Why is this happening??
Do you know how to do this in octave too?
k = (0:1000);
k_sum = sum(1./((2*k)+1).^2);
disp(k_sum)
It's interesting that you jumped straight to using syms when the basic matlab functions work perfectly well for this problem. Why is that?
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Is it possible to plot bars with filled pattern in Matlab, like this figure?
I attempted to use applyhatch_pluscolor link however, I couldn't make it work (attempt below). Is there an easy / feasible alternative?
Test code:
bar(rand(3,4));
[im_hatch,colorlist] = applyhatch_pluscolor(gcf,'\-x.',1,[],[],150);
Then I changed the source code, from bits = hardcopy(h,'-dzbuffer',['-r' num2str(dpi)]); to bits = print(h,'-RGBImage',['-r' num2str(dpi)]);.
I got the figure below. However, this is still far away form the desired result.
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I have been trying for a while to get this to work but I don't seem to be getting any closer to a solution.
I'm not sure of what the pattern is and what to write for the "d" value in a:d:b
Clearly you want to start from 0 (a) and go to 2*pi (b).
Now the question comes what is your step size (d)?
From your example you can see that you are changing from 0 to pi/n.
And from pi/n to 2*pi/n.
This means your step size is d=pi/n
Once you defined your n, e.g:
n=10;
you can do the rest like this:
x=0:(pi/n):(2*pi)
y=sin(x);
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This figure illustrates my problem:
t (in the X1 calculation) value changes from 0 to etz. If its value reaches etz it has to start from 0 again and again.
This situation has to continue during simulation (I need a loop!). However, t is simulation time and I cannot force it to be zero. So maybe I need a parallel time to the simulation time but I don't how to create it.
Use modulo operator.
http://www.mathworks.com/help/matlab/ref/mod.html
For example:
X1 = abs((mod(t,e*tz)-e*tz/2)/(1.125*c*tz))
This part:
mod(t,e*tz)
Will be >= 0 and < e*tz and will repeat the way you want.
In the future, please provide a better title for your question. Also, providing a screen shot of your code is not the preferred way to include code.
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This is rather a general question.
Actually I have a value x=-77 (dBm) and I want to change it to dB so the command would be y=pow2db(x). The problem is it does not accept negative values. So how do I change this to non-negative and then calcuate y?
Your comments are highly appreciated.
Thanks in advance
You can use the abs() function Matlab provides.
example:
abs([-2 2])
ans=
2 2
Still check what you are doing. Logarithms work in a special way, and you may not be wanting the logarithm of the absolute... just check :D
I would guess one of these two possibilities:
y = pow2db(abs(x))
or
y = pow2db(abs(x)) *sign(x)
Not sure whether either one of them would be meaningfull though.