結果:
Hi all,
I want to solve an ode45 equation for a multibody model. The matrixes I have to implement in the ode45 are very big. Now I am using the subs function to place the values for x into the matrixes. However because the fact that this is done inside the ode45 function running the function takes a while. Is there a way to already implement the x value in the matrixes as a variable outside the ode45 function?
In the code WT and w_bar are matrixes of 12x15 and12x1
The vector hulp_vec and hulp_vec_derivative contain both 15 syms variables
% Solve the equation
[t,x]=ode45(@(t,x)analytical_simplified(t,x,M,H,S,WT,w_bar,N,constr_eq,hulp_vec,hulp_vec_derivative),tspan,x0);
function [dx, lambda, constraint_eq]=analytical_simplified(t,x,M,H,S,WT,w_bar,N,constraint_eq,hulp_vec,hulp_vec_derivative)
tic
tau=[0;sin(t);0];
%make matrices afhankelijk van x and dx
% WT=subs(WT,hulp_vec',x(1:N));
WT=subs(WT,hulp_vec_derivative',x(N+1:2*N));
w_bar=subs(w_bar,hulp_vec',x(1:N));
w_bar=subs(w_bar,hulp_vec_derivative',x(N+1:2*N));
constraint_eq=subs(constraint_eq,hulp_vec',x(1:N));
toc
tic
Minv=inv(M);
% Stabilize the matrixes
wo=100;
alpha=wo/5; beta=1;
w_bar_stab = w_bar + 2*alpha*beta*WT*x(N+1:2*N) + alpha^2*constraint_eq;
% w_bar_stab=w_bar;
L1=(WT*Minv*WT');
L2=(WT*Minv*(H-S*tau)-w_bar_stab);
L1=double(L1); L2=double(L2);
lambda=L1\L2;
ddx=Minv*(S*tau-H+WT'*lambda);
dx(1:N)=x(N+1:2*N);
dx(N+1:2*N)=ddx;
dx=dx';
dx=double(dx);
toc
end
With kind regards,
Janne
Good day community, can I know what is this symbol could be? It looks like a ramp/ continuous ramp. But I believe it is not both them. I saw someone connect it after a voltage/ current measurement. Can I know what is the function of this symbol too? Much appreciate for the answers given
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Hello All,
I was wondering, from which version Tracebility Diagrams are available (in SLK Req)?
Regards
Abhishek KUMAR
Hello, I am trying to use a Velodyne VLP 16 Puck Lidar, to receive live data (visualized) as well as point cloud, the issue I have is; I do actually run the code to visualize the lidar and I can see the live map, as well as I get frames in the work space as (1x1 Pointcloud), now how can I process these pointclouds(from the live stream of lidar), I would like to denoise them, downsample, etc. I tried going through alot of toolboxes but I usually get stuck, need tips and how to start working, thanks.,
unable to download and cant install Arduino third party packages , but support packeages are download, 
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please find the attached code"ex1_AP_STA.m" and output data of simulator "Simulation data.zip"
when i use command openExample('px4/PX4HITLSimulationFixedWingPlantSimulinkExample')，matlab shows "PX4HITLSimulationFixedWingPlantSimulinkExample" cannot find. So does somebody know how to find this demo? Thanks.
ncorr is not working on MATLAB 2023b new version, it gives me an error. Does somebody know why? Thanks
I know the latest version of MATLAB R2023b has this feature already, put it should be added to R2023a as well because of its simplicity and convenience.
Basically, I want to make a bar graph that lets me name each column in a basic bar graph:
y=[100 99 100 200 200 300 500 800 1000];
x=["0-4" "5-17" "18-29" "30-39" "40-49" "50-64" "65-74" "75-84" "85+"];
bar(x,y)
However, in R2023a, this isn't a feature. I think it should be added because it helps to present data and ideas more clearly and professionally, which is the purpose of a graph to begin with.
Dear all,
In an excel file, we have temperature (te) and humidity (hu) data in two columns. The Gaussian kernel-density estimation and best-fit quadratic curve were plotted. However, we need to determine whether the relationship is statistically significant or not, as well as the coefficient of determination (R2). For calulation of the both of them, we used functions like:
2. statistically significant p= coefTest(aa)
Is it correct? If not, please provide the any other suggestions.
Thank you.
For example, my main line chart have values: X=[10 20 30 40 50] Y=[0.5 1.5 5 -6 4]. I need to add second X axis, with value [1 2 3 4 5] but but I would like the distance between individual points to be variable. For example, between points 1-2 d=25, between 2-3 d=10. I would like to define this distance freely.
xt = e^-3t
ht= -5e^-2t +6e^-3t
so ofcourse these would be used to plot yt which is xt*ht in other words xt conv ht. Thanks for your assistance!!
Recently, I came across a post about the JIT compiler on this Korean blog. In the post. The writer discussed the concept of the "Compile Threshold" and how it is calculated.
"The JVM accumulates the number of calls for each method called and compiles when the number exceeds a certain number. In other words, there is a standard for checking how often it is called and then deciding, 'It is time to compile.' This standard is called the compilation threshold. But what is this and why should it be used as a standard?"
The concept of the "Compile Threshold," as used above, seems to be more commonly associated with Tracing just-in-time compilation.
The writer used the simple Java code below to calculate the threshold.
for (int i = 0; i < 500; ++i) {
long startTime = System.nanoTime();
for (int j = 0; j < 1000; ++j) {
new Object();
}
long endTime = System.nanoTime();
System.out.printf("%d\t%d\n", i, endTime - startTime);
}
Since the MATLAB execution engine uses JIT compilation, I just wanted to perform the same experiment that the writer did.
I experimented using simple codes based on the code in the blog. I iterated a function 500 time using for-loop and calculated the execution time for each iteration using tic and toc. Then I plotted the execution time for each loop as blow. First five execution times are much higher than followings (10 times!) The test is very rough so I am not sure that I can conclude "MATLAB has Compile Threshold and it is 5!" but this value is actually correct ;-)
t0 = 0;
tfinal = 10;
y0 = [20;20];
timeToRun = zeros(500,1);
for i = 1:500
tStart = tic;
[preypeaks,predatorpeaks] = solvelotka(t0, tfinal, y0);
tEnd = toc(tStart);
timeToRun(i) = tEnd;
end
VS Code Extension for MATLAB was introduced back in April and has been downloaded 75K times since. Do people here use VS Code for writing MATLAB code?
Would it be a good thing to have implicit expansion enabled for cat(), horzcat(), vertcat()? There are often situations where I would like to be able to do things like this:
x=[10;20;30;40];
y=[11;12;13;14];
z=cat(3, 0,1,2);
C=[x,y,z]
with the result,
C(:,:,1) =
10 11 0
20 12 0
30 13 0
40 14 0
C(:,:,2) =
10 11 1
20 12 1
30 13 1
40 14 1
C(:,:,3) =
10 11 2
20 12 2
30 13 2
40 14 2
Wait for Walter, the rest of us are mere users.
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