Options Syntax

Use theodeset函数创建一个选项结构then pass to the solver as the fourth input argument. For example, to adjust the relative and absolute error tolerances:

opts = odeset('RelTol',1e-2,'AbsTol',1e-5); [t,y] = ode45(@odefun,tspan,y0,opts);

If you use the commandodesetwith no inputs, then MATLAB^®displays a list of the possible values for each option, with default values indicated by curly braces{}.

Theodegetfunction queries the value of an option in an existing structure, which you can use to dynamically change option values based on conditions. For example, this code detects whetherStatsis set to'on', and changes the value if necessary:

ifisempty(odeget(opts,'Stats')) odeset(opts,'Stats','on')end

Compatibility of Options with Each Solver

Some options inodesetare generic and compatible with any solver, while others are solver-specific. This table summarizes the compatibility of each option with the different solvers.

* Use theNonNegativeparameter withode15s,ode23t, andode23tbonly for those problems in which there is no mass matrix.

** The events function forode15imust accept a third input argument foryp.

Usage Examples

MATLAB includes several example files that show how to use various options. For example, typeedit ballodeto see an example that uses'Events'to specify an events function, oredit batonodeto see an example that uses'Mass'to specify a mass matrix. For a complete summary of example files and which options they use, seeSummary of ODE Examples and Files.