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# Matlab help required Watch

1. not sure if in the right place

Is anybody here proficient in MATLAB?

There's some help I require and I can't get a response from anybody on the official forum.
2. What are you having problems with?
3. I know a bit.
ServantOfMorgoth
13 1 20 8 42

Guys can you help?
5. (Original post by BlueSam3)
What are you having problems with?
Would I be able to PM you?
6. (Original post by Eternalflames)
ServantOfMorgoth
13 1 20 8 42

Guys can you help?
I already told him im ok at best with matlab. I hope he gets help though.
7. Sure, PM me if you like. Or just post it here.
8. Spoiler:
Show
% Practical 9
% A script to plot two 3D waves.

clear
%Define the total time for simulation
T_total=10;
%Set the computation increment
dt=0.1;
%calculate the number of steps
ntstep=T_total/dt+1;
%Define Input Waves
alphaa=1; %velocity of wave a
alphab=2; %velocity of wave a

fa=1; %frequency of wave a
fb=0.5; %frequency of wave b
ampa=6; %amplitude of wave a in cm
ampb=3; %amplitude of wave b in cm

%set the source depth
depth=1;

%Calc wave parameters using input
Ta=1/fa; %period of wave a
Tb=1/fb; %period of wave a
wa=2*pi*fa; %angular frequency of wave a
wb=2*pi*fb; %angular frequency of wave b
la=Ta*alphaa;%wavelength of wave a
lb=Tb*alphab;%wavelength of wave b
ka=2*pi/la; %wavenumber of wave a
kb=2*pi/lb; %wavenumber of wave b

x=(-1010); %x
y=(-1010); %y
z=(-200); %z
t=zeros(length(x),length(y), length(z)); %start time
% setup the figure
figure(1);

%label axes
xlabel('Distance (m)');
ylabel('Distance (m)');
zlabel('Depth (m)');
hold on
[X,Y,Z]=meshgrid(x,y,z);
R=sqrt(X.^2+Y.^2+(Z+depth).^2);
%loop over nsamp
for n=1:ntstep
t=t+dt; %time
arga=wa*t-ka*R; %argument of wave a
argb=wb*t-kb*R; %argument of wave b
a=ampa*sin(arga)./max(1,R);
a(R>t.*alphaa)=0; % causality condition
a(R<t.*alphaa-la/2)=0; % limit lenght of input wave to one half cycle
b=ampb*sin(argb)./max(1,R);
b(R>t.*alphab)=0; % causality condition
b(R<t.*alphab-lb/2)=0; % limit lenght of input wave to one half cycle

figure(1);
hold off;

wf=a+b;
slice(X,Y,Z,wf,x,y,z);
axis square;
caxis([0,1]);
colormap([[0:0.1:1]',zeros(length([0:0.1:1]'),1),zeros(length([0:0.1:1]'),1)]);
col=colorbar;
alpha(0.05);
hold on;
%label axes
xlabel('Distance (km)');
ylabel('Distance (km)');
zlabel ('Depth (km)');
ylabel(col,'Amplitude (cm)'); % label the colour bar

title(strcat('time = ', num2str(t(1)), ' s'));
pause (dt);

end

I need to add a contour plot to show the displacement at the surface of the animation (so only in X-Y plane - I'll attach a photo to clarify if required) to show displacement. Using contour(X,Y) doesn't quite work.

Then I need to add a subplot to show displacement against time at the surface at any chosen point [X,Y,0]
9. Nobody?
10. Okay i've figured it out...

but now I'm stuck on something else.

Not that any of you care.

11. (Original post by hezzlington)
Okay i've figured it out...

but now I'm stuck on something else.

Not that any of you care.

Next time you have issues talk to me. I will surely help!
Next time you have issues talk to me. I will surely help!
How good are you? I'm planning to do my final year project on matlab and I'm pretty rubbish at it. I'd need loads of help 😅

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Next time you have issues talk to me. I will surely help!
i have issues can you help me

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