How to plot ODE function and I don't get this plot.

[Rena Berman]

(Answers dev) Restored edit.

Answer 1

[Torsten]

Solve the ODEs using ODE45, e.g., and use "plot3" for the plot.

Best wishes

Torsten.

[Torsten]

function main
%Set initial values for r, theta, z
r00 = 10;
theta00 = 0;
z00 = 1.0;
y0 = [r00 theta00 z00];
% Set model parameters
z0 = 0.0;
a = 0.1;
gamma_inf = 1000.0;
nu = 1.0;
% Set integration period
tspan = 0:0.05:10;
% Call integrator
fun = @(t,y)[-a*y(1);gamma_inf/(2*pi*y(1)^2)*(1-exp(-a*y(1)^2/(2*nu)));2*a*(y(3)-z0)];
[T Y] = ode45(fun,tspan,y0)
R = Y(:,1);
THETA = Y(:,2);
Z = Y(:,3);
% Convert polar to cartesian coordinates
[x y] = pol2cart(THETA,R)
% Plot spiral
plot3(x,y,Z)

[Myo Gyi]

Thank you very much sir..... You are very kind and helpful.