How do I solve these differential equations using a while loop?
2 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
Christopher Maraj
am 11 Mär. 2018
Kommentiert: Christopher Maraj
am 12 Mär. 2018
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/171151/image.png)
1 Kommentar
Roger Stafford
am 11 Mär. 2018
Bearbeitet: Roger Stafford
am 11 Mär. 2018
If you want to allow delta t to approach zero as a limit, you can solve these equations using one of the ode functions. The first equation, for example, would have the form:
dU/dt = k1-k2*X./((X.^2+Y.^2+Z.^2).^(3/2))
On the other hand if you wish to solve them using delta t as a fixed nonzero value, then do so with a for-loop to provide the iteration, not a while-loop. Just carry out the operations you have given here within the for-loop at each step going from the n-th values to the n+1-st values.
Akzeptierte Antwort
Abraham Boayue
am 12 Mär. 2018
i = 1;
while i <= n-2
i = i +1;
% write all your code
% here. This will produce
% the same results as the
% for loop.
end
1 Kommentar
Abraham Boayue
am 12 Mär. 2018
You change the for loop to the while loop above, it does the same operation as the for loop.
Weitere Antworten (1)
Abraham Boayue
am 12 Mär. 2018
clear variables
close all
% Define parameters
dt = dt;
t = t0:dt:tf;
n = length(t);
m = m;
thx = thx;
thy = thy;
thz = thz;
G = G;
Me = Me;
% Initializations Initial conditions Boundary conditions
u = zeros(1,n); u(1) = u0; u(n) = un;
v = u; v(1) = v0; v (n)= vn;
w = v; w(1) = w0; w(n) = wn;
x = w; x(1) = x0; x(n) = xn;
y = x; y(1) = y0; y(n) = yn;
z = y; z(1) = z0; z(n) = zn;
for i = 2: n-1
u(i+1) = u(i) + (thx/m - G*Me*(x(i)/(x(i)^2 +y(i)^2 +z(i)^2)^(3/2)))*dt;
v(i+1) = v(i) + (thy/m - G*Me*(y(i)/(x(i)^2 +y(i)^2 +z(i)^2)^(3/2)))*dt;
w(i+1) = w(i) + (thz/m - G*Me*(z(i)/(x(i)^2 +y(i)^2 +z(i)^2)^(3/2)))*dt;
x(i) = x(i) + u(i+1)*dt;
y(i) = y(i) + v(i+1)*dt;
z(i) = z(i) + w(i+1)*dt;
end
figure;
plot(t,u,'linewidth',2);
hold on
plot(t,v,'linewidth',2);
plot(t,w,'linewidth',2);
plot(t,x,'linewidth',2);
plot(t,y,'linewidth',2);
plot(t,z,'linewidth',2);
a = ylabel('Pressure');
set(a,'Fontsize',14);
a = xlabel('x');
set(a,'Fontsize',14);
a=title(['Solution to system of ode - dt = ' num2str(dt)]);
legend('u', 'v','w','x','y','z')
xlim([0 1]);
set(a,'Fontsize',16);
grid;
5 Kommentare
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!