The mesh function is not working for me in offline Matlab, but when I check this code in online Matlab, it works. What is the reason?

[John D'Errico]

A picture may be worth a thousand words, but a picture of something in front of what you want to show? No words can possibly describe it.

Is there a good reason why you wanted to make it impossible to get help? I would suggest you post somethign someone can actually see.

Better help yet would involve you showing what error message arises, when you try to use mesh. It would also ask you to show the results of

which mesh -all

What I really want to say is: "This is a fine mesh you've gotten us into", but not all people will recognize the hacked quote.

[Kuvon]

function [] = app()

X = pi;

T = pi/2;

a = 1;

m = 80;

n = 40;

k = 120;

h_p = X / m;

x_p = linspace(0, X/2, m + 1);

t_p_c = linspace(0, T/4, floor(n/2) + 1);

t_p_f = linspace(T/4, T/2, 2*k);

tau_p = t_p_c(2) - t_p_c(1);

tau_f = t_p_f(2) - t_p_f(1);

u0 = sin(x_p);

v_p = zeros(m + 1, length([t_p_c t_p_f(2:end)]));

g1 = @(t) -sin(6*t);

g2 = @(t) sin(1/2*t);

v_p(:, 1) = u0;

v_p(:, 2) = u0;

for j = 2:length(t_p_c) - 1

v_p(1, j + 1) = g1(t_p_c(j + 1));

v_p(end, j + 1) = g2(t_p_c(j + 1));

for i = 2:m

v_p(i, j + 1) = a^2 * (tau_p / h_p)^2 * (v_p(i - 1, j) - 2 * v_p(i, j) + v_p(i + 1, j)) - v_p(i, j - 1) + 2 * v_p(i, j);

end

end

offset = length(t_p_c);

for t = 1:length(t_p_f) - 1

idx = offset + t;

v_p(1, idx) = g1(t_p_f(t + 1));

v_p(end, idx) = g2(t_p_f(t + 1));

for i = 2:m

v_p(i, idx) = a^2 * (tau_f / h_p)^2 * (v_p(i - 1, idx - 1) - 2 * v_p(i, idx - 1) + v_p(i + 1, idx - 1)) - v_p(i, idx - 2) + 2 * v_p(i, idx - 1);

end

end

total_time = [t_p_c t_p_f(2:end)];

figure;

mesh(total_time, x_p, v_p);

xlabel('T');

ylabel('X');

zlabel('u(x,t)');

end

----------------Can you please check this code, I still have a problem.

[Torsten]

What do you get as output if you type

which error -all

built-in (/MATLAB/toolbox/matlab/lang/error)
/MATLAB/toolbox/matlab/connector2/logger/+connector/+internal/Logger.p  % connector.internal.Logger method
built-in                                                                % gpuArray method

which mesh -all

/MATLAB/toolbox/matlab/graphics/graphics/graph3d/mesh.m

?

Did you somewhere create your own function mesh.m or error.m ? Then rename it / them .

[Kuvon]

Thank you very much, I fixed them, the mathlab is working now.

Answer 1

[Star Strider]

We do not have access to your computer.

Run these from your Command Window or a script:

restoredefaultpath

rehash toolboxcache

and try it again. If it is still not working after that, Contact Support.

[Star Strider]

Sure!

It seems to work correctly here —

    X = pi; 
    T = pi/2; 
    a = 1; 
    m = 80;              
    n = 40;              
    k = 120;              
    
    h_p = X / m; 
    x_p = linspace(0, X/2, m + 1);  
    t_p_c = linspace(0, T/4, floor(n/2) + 1); 
    t_p_f = linspace(T/4, T/2, 2*k);        
    tau_p = t_p_c(2) - t_p_c(1); 
    tau_f = t_p_f(2) - t_p_f(1);     
    
    u0 = sin(x_p); 
    v_p = zeros(m + 1, length([t_p_c t_p_f(2:end)]));
    g1 = @(t) -sin(6*t); 
    g2 = @(t) sin(1/2*t); 
    v_p(:, 1) = u0;
    v_p(:, 2) = u0; 
   
    for j = 2:length(t_p_c) - 1
        v_p(1, j + 1) = g1(t_p_c(j + 1));
        v_p(end, j + 1) = g2(t_p_c(j + 1));
        
        for i = 2:m
            v_p(i, j + 1) = a^2 * (tau_p / h_p)^2 * (v_p(i - 1, j) - 2 * v_p(i, j) + v_p(i + 1, j)) - v_p(i, j - 1) + 2 * v_p(i, j);
        end
    end
   
    offset = length(t_p_c);
    for t = 1:length(t_p_f) - 1
        idx = offset + t;
        v_p(1, idx) = g1(t_p_f(t + 1));
        v_p(end, idx) = g2(t_p_f(t + 1));
        
        for i = 2:m
            v_p(i, idx) = a^2 * (tau_f / h_p)^2 * (v_p(i - 1, idx - 1) - 2 * v_p(i, idx - 1) + v_p(i + 1, idx - 1)) - v_p(i, idx - 2) + 2 * v_p(i, idx - 1);
        end
    end
   
    total_time = [t_p_c t_p_f(2:end)];
    figure;
    mesh(total_time, x_p, v_p);
    xlabel('T');
    ylabel('X');
    zlabel('u(x,t)');

●

It also works correctly when I run it offline on my computer.

.

[Kuvon]

ooooooo Thank you very much, I fixed them, the mathlab is working now.

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

.