Saving data in a 3d array in for loop

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Lisa Goh
Lisa Goh 2017-6-29
回答： KSSV 2017-6-29
Hi! I am running a 6 equation ode solver which generates a 1001x6 matrix in a for loop. I am trying to generate a 3d matrix (1001x6xi) which stores the data after each iteration and plot the resultant values against i, but I end up getting all zeros as my values. Is there anything wrong with my code?
Here's my code:
for i=1:1:351
initial_f=[0 0 (i-51)*1e-6 0 0 0];
%ODE solver
t=(0:10:10000)*1e-15;
options=odeset('reltol',1e-15,'abstol',1e-20);
[t,f]=ode15s('lorentz_force',t,initial_f,options);
%preallocate F (3d matrix)
F=zeros(1001,6,i);
F(:,:,i)=f(i);
%extracting values
X=F(:,1,:);Y=F(:,2,:);Z=F(:,3,:);
PX=F(:,4,:);PY=F(:,5,:);PZ=F(:,6,:);
p_x=PX(1001,:);
p_y=PY(1001,:);
p_z=PZ(1001,:);
p_r= sqrt((p_x.^2)+(p_y.^2)+(p_z.^2));
Energy_total=sqrt(((p_r).^2).*(c^2)+((m^2)*(c^4)));
Energy_initial=m*c^2;
Energy_gain=Energy_total-Energy_initial;
%plotting against i
plot((i-51)*1e-6,Energy_gain./e)
xlabel ('z_0 (m)')
ylabel ('Energy Gain (eV)')
end
end
The six equations are stored in another function 'lorentz_force'. Thank you so much in advance!

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回答（1 个）

KSSV
KSSV 2017-6-29
F = rand(1001,6) ;
% conver F into 3D
% using loop
F3D = zeros(1001,1,6) ;
for i = 1:6
F3D(:,:,i) = F(:,i) ;
end
% reshaping
F1 = reshape(F,1001,1,6) ;

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