`ode23s`

One-step solver for stiff differential equations, based on a modified Rosenbrock formula.

Category: Mathematics > Numerical Integration and Differential Equations

Syntax

[t, y] = ode23s(odefun, tspan, y0)

Integrates the stiff system y' = odefun(t, y).

[t, y] = ode23s(odefun, tspan, y0, options)

Also applies options from odeset; supplying 'Jacobian' improves speed.

Description

As a one-step method it needs no history, so it restarts cleanly after a discontinuity and can be more efficient than ode15s at crude tolerances. It forms and factors the Jacobian at each step, so for large systems giving a sparse Jacobian matters.

Use it when ode45 takes very small steps although the solution looks smooth.

Input arguments

odefun: Handle dydt = odefun(t, y).
tspan: [t0 tf] or a vector of output times.
y0: Vector of initial values.

Output arguments

t, y: Time points and solution, laid out as for ode45.

Example

Stiff decay

f = @(t, y) -100*(y - cos(t));
[t, y] = ode23s(f, [0 1], 0);
fprintf('%.3f\n', y(end))

Output

0.549

ode23s