Using 3 dimensional array to 2d-plot????
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I need to use this 3 arrays into 2 equations to 2d-plot
w=0:1:100;
mu4=0:0.01:1;
lam4=0:0.01:1;
the equation is given below
code for the above equation is given below
th1=cos(lam4*(pmr/2));
th2=cos((1+lam4)*(pmr/2));
th3=cos((lam4+mu4)*(pmr/2));
th4=sin(mu4*(pmr/2));
th5=sin(lam4*(pmr/2));
ki=((-w^(3+lam4))+(42.46*(w^(1+lam4)))+(100*w^(mu4+lam4)*th4))/(250*th5)
kp=(-1/(250*(w^lam4)*th1))*(((-w^(3+lam4))*th2)+((42.46*w^(1+lam4))*th2)...
-(15.88*(w^(2+lam4))*th1)+(106.2*(w^lam4)*th1)+(100*(w^(lam4+mu4))*th3)...
+250*ki)
all the three array need to used together into the equation and get plot as the graph given below
How can i use the 3 dimensional array to plot the graph above.. please help me or suggest me some hints.
Thank you.
Nitesh
回答（2 个）
Star Strider
2015-9-30
At the very least you need to vectorise your equations to get vectors of ‘ki’ and ‘kp’:
ki=((-w.^(3+lam4))+(42.46*(w.^(1+lam4)))+(100*w.^(mu4+lam4).*th4))./(250*th5);
kp=(-1./(250*(w.^lam4).*th1)).*(((-w.^(3+lam4)).*th2)+((42.46*w.^(1+lam4)).*th2)...
-(15.88*(w.^(2+lam4)).*th1)+(106.2*(w.^lam4).*th1)+(100*(w.^(lam4+mu4)).*th3)...
+250*ki);
You did not provide ‘pmr’, and the values for your variables (and your equations) will not give you the full loop in the image. I leave that to you to sort out.
4 个评论
Nitesh
2015-9-30
Star Strider
2015-9-30
The impression I get is that you are calculating ‘kp’ and ‘ki’ from your three vectors, then plotting them:
plot(ki, kp)
The plot you show is not a surface plot.
Nitesh
2015-9-30
Star Strider
2015-9-30
I have no idea why your code is not reproducing the 2D plot you posted. (I have no idea what you are even doing.) I vectorised your ‘kp’ and ‘ki’ assignments and got them to work.
I must leave it to you to be sure they — and the rest of your code — are otherwise correct.
At the very least, you need to switch your i=i+1 and k=k+1 statements: you have k indexing the inner-most loop, and i indexing the outer-most, but the increments are swapped. You also need to change ki in you statement for kp to ki(i, j, k).
You might also want to try plotting using
plot(ki(:), kp(:), '.')
I'm not sure this is going to give you what you want. I'm pretty sure that a fair number of your roughly 1 million data points will be inf and NaN...
Consider the following, which should be equivalent:
n = 100;
omega = linspace(0, 100, n + 1);
mu = linspace(0, 1, n + 1);
lambda = linspace(0, 1, n + 1);
[Omega, Mu, Lambda] = ndgrid(omega, mu, lambda);
K_i = -(...
-(Omega.^(3 + Lambda)) + ...
42.46*(Omega.^(1 + Lambda)) + ...
100*(Omega.^(Lambda + Mu)).*sin(Mu*pi/2)...
)./(250*sin(Lambda*pi/2));
K_p = -(...
-(Omega.^(3 + Lambda)).*cos((1 + Lambda)*pi/2) + ...
42.46*(Omega.^(1 + Lambda)).*cos((1 + Lambda)*pi/2) + ...
-15.88*(Omega.^(2 + Lambda)).*cos(Lambda*pi/2) + ...
106.2*(Omega.^(Lambda)).*cos(Lambda*pi/2) + ...
100*(Omega.^(Lambda + Mu)).*cos((Lambda + Mu)*pi/2) + ...
250*K_i ...
)./(250*(Omega.^Lambda).*cos(Lambda*pi/2));
figure; plot(K_p(:), K_i(:), '.')
It would appear that you're trying to plot the stability regions for a PID controller. I'm not sure this is the best approach...
2 个评论
Looking more closely at your (updated) problem, the plot you show (Figure 5) that indicates that mu and lambda are fixed in the plot ( 1.15 and 0.9, respectively). I assume that means the plot in the figure is essentially a parametric plot as a function of omega.
However, it doesn't seem like fixing these values in the code above reproduces the plot, though I might have made a mistake...
arich82
2015-9-30
Note: I appear to have made an error in my first post: the expression for K_i has a leading negative sign which shouldn't be there.
(This also invalidates the values for K_p, and both plots, but the comments about the inf and NaN, the parametric nature of the plot, and the suggested range for omega still stand.)
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