Unable to meet integration tolerances without reducing the step size below t

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jixie zhuangbei 2015-4-13

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https://ww2.mathworks.cn/matlabcentral/answers/198858-unable-to-meet-integration-tolerances-without-reducing-the-step-size-below-t

评论： jixie zhuangbei 2015-4-14

Warning: Failure at t=5.422028e-006. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (1.355253e-020) at time t. > In ode45 at 355 In ODE45_main at 4 Warning: Function call Xlabel invokes inexact match D:\MATLAB7\toolbox\matlab\graph2d\xlabel.m.

> In ODE45_main at 15 Warning: Function call Ylabel invokes inexact match D:\MATLAB7\toolbox\matlab\graph2d\ylabel.m.

> In ODE45_main at 15 The element type "name" must be terminated by the matching end-tag "</name>". Could not parse the file: d:\matlab7\toolbox\ccslink\ccslink\info.xml >>

【 Failure at t=5.422028e-006. Unable to meet integration tolerances without reducing the step size below the smallest value allowed (1.355253e-020) at time t.】

Can we reset the value of the integration tolerances or the smallest value allowed?

For example， the smallest value allowed can be increasd？ The step size can be decreased？

If it is feasible， how can I reset it？

Would you give me a example？

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Torsten 2015-4-13

You will have to show us your MATLAB code in order to find possible reasons for the error message.

Best wishes

Torsten.

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Answer 1

Thomas Koelen 2015-4-13

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Often that warning means that your system of ODEs is stiff. See section 7.9 of the ODE chapter of Cleve's "Numerical Computations with MATLAB" for more information about stiffness:

http://www.mathworks.com/moler/chapters.html

Try a stiffer solver, like ODE15S or ODE23S.

http://www.mathworks.com/access/helpdesk/help/techdoc/ref/ode113.html