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Cannot understand about this

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Byeongchan Min
Byeongchan Min on 25 Apr 2020
Answered: Sriram Tadavarty on 27 Apr 2020
Below is my code:
When I proceed this, I can get 2 lines, one of which I cannot understand.
1st one is an expected, diverging line to negative infinity, but the other I get is y=x+1 line...
Where is it from?? I cannot figure it out :(
Moreover if I add plot of z11 as well using plot(z11, '-k.') and hold on,
z11 plot also follows the y=x+1 line, while it never does alone!!!! OMG WHY IS IT
a=2.95; x11=0.5; x12=-0.001; i=0;
z11=[i x11]; z12=[i x12];
while i<50
y11=f(a,x11); y12=f(a,x12);
x11=y11; x12=y12; i=i+1;
z11=[z11; [i y11]]; z12=[z12; [i y12]];
end
figure(1)
title('alpha=2.95')
subplot(2,2,1)
plot(z12,':rd')
axis([0 50 -1 1])
function f=f(a,x); f=a*x*(1-x); end

  3 Comments

Sriram Tadavarty
Sriram Tadavarty on 25 Apr 2020
You observe as such because you plot both i and the actual value in z11 and z12. Implies z11 and z12 are M x 2 matrix. Plot the second column only and it would provide the expected results. Try plot(z12(:,2), ':rd')
Byeongchan Min
Byeongchan Min on 26 Apr 2020
wow it worked thx!!! I think it'll take longer to understand it thoroughly though :D
Sriram Tadavarty
Sriram Tadavarty on 27 Apr 2020
Glad that it helped.
I will place the same in answer

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Answers (1)

Sriram Tadavarty
Sriram Tadavarty on 27 Apr 2020
Hi Byeongchan,
This observation is becuase the variable i and actual value in z11 and z12 are plotted. Since the effect values of z11 and z12 are a matrix of M x 2. Both the columns of them are plotted.
To have the proper plot, use the second colmn itself and it would provide expected results.
Try plot(z12(:,2), ':rd')
For more details, look at plot.
Hope this helps.
Thanking you.
Regards,
Sriram

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