How to become aware of failure of ode45 without looking at the displayed warning?

matlab, ode

Solution

You can turn that `warning` into an `error`, and errors can be caught by `try/catch` blocks.

An example:

% Change this particular warning into an error
warnId = 'MATLAB:ode45:IntegrationTolNotMet';
warnstate = warning('error', warnId);    

% That can be caught with try/catch
try     
    % Quick-failing integration, suggested by horchler
    [t,y] = ode45(@(t,y)[y(1)^2;y(2)],[0 1],[1;1]);

catch ME
    % Check if we indeed failed on meeting the tolerances
    if strcmp(ME.identifier, warnId)

        % DO YOUR STUFF HERE

    else
        % Something else has gone wrong: just re-throw the error
        throw(ME);
    end

end

% Don't forget to reset the warning status
warning(warnstate);

You can get the `warnId` of any warning by virtue of the `lastwarn` command. For errors, see `lasterr`.

Problem

When the solution of ODE45 diverges (doesn't matter why and how), the following warning will be displayed, and the solver can not continue: Warning: Failure at t=8.190397e+01. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (2.273737e-13) at time t. I am running ode45 on a matrix (lots of inputs), so I want to find out automatically for which inputs the above condition(failure) happens. I mean, Is there any other sign of this condition returned by ode45 that can be written in an array automatically? Something that can be used in a `if` statment as: `if {some variable is returned/is equal to ...} then {the solver has failed}` to identify those faulty inputs automatically without looking for the displayed warning.

Original source