MATLAB程序.rar_ODE 微分方程_ode_ode解微分方程_微分方程_解微分方程

function f1 %define tstart, tend and the number of time steps you want to take, n: tstart = 0; tend = pi/2; n = 160; tspan = linspace(tstart,tend,n); %define the initial conditions making sure to use the right ordering xinit = [0;0;0]; %Get x. I have left options as the default value so it's not included in the function call below [t,x] = ode45(@integratingfunction, tspan, xinit) %define the output variables: y = x(:,1); ydot = x(:,2); ydotdot = x(:,3); %Include whatever plotting functions you need to include here. You can plot anything you want: %y(t), _y(t), _y(y), _y(y), etc. subplot(y(t),t) plot %plot3( ... ) % use this is you are plotting a 3D plot title(' ') xlabel('t ') ylabel('y ') %zlabel(' ') % uncomment the last line if you are doing a 3D plot %|||||||||||||- %THE INTEGRATION FUNCTION % This can either be in a separate or right at the bottom of the same le. %Either way, the syntax is as follows: function dxdt = integratingfunction(t,x) %1. Define your constants - mass, gravity, etc. %2. Define new variables: y=x(1), ydot=x(2), etc %You don't have to do this, but is makes it a lot easier for others to decipher your code %3. Write out your rst order system of ODE's: dxdt = zeros(size(x)); dxdt(1) = ydot; dxdt(2) = 5/(0.5*sin(y)-cos(y));