Turn variable-step solution into fixed-step

I am simulating a system that is very stiff and nonlinear using ODE23s. I need the variable step-length for the simulation to be stable. After the simulation I m going to analyse the dynamics of the system in a different program, and I need all my simulations to have the same length. Anyone has any experience making the simulation output uniformly sampled? Is this some setting in the ODE-solver or could I possibly use interp1?

Answer 1

[Star Strider]

The ODE solvers are adaptive, but if you want all the results to have the same row length, you can specify the ‘tspan’ argument to have a specific length. The ODE solvers will output the closest results to the desired ‘tspan’ values that it estimates. You will not need to interpolate the results:

t0 = ...;                               % Start Time
tf = ...;                               % End Time
N  = ...;                               % Number Of Time Values (Row Length Of Results)
tspan = linspace(t0, tf, N);

ic = [...];                             % Initial Conditions Vector
[t,y] = ode45(@odefun, tspan, ic);

You can use the same construction to integrate all your ODE functions.