How to deal with very small and very large parameter values while solving DAE?

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Monisha S R 2018-10-23

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https://ww2.mathworks.cn/matlabcentral/answers/425509-how-to-deal-with-very-small-and-very-large-parameter-values-while-solving-dae

编辑： Monisha S R 2018-10-26

I have to solve a system of differential algebraic equations wherein some of the parameter values are very large (e.g. of the order of 10^5 to 10^10) and some other parameter values are very small (e.g. order of 10^-4 to 10^-6). I use ode15s, but the code breaks saying:

Warning: Failure at t=1.000000e-03.  Unable to meet integration tolerances without reducing the step size below the smallest value allowed
(3.552714e-18) at time t.

How do I resolve this?

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Torsten 2018-10-26

When you generate the vector of time derivatives, just omit the semicolon at the end of the line.

Monisha S R 2018-10-26

编辑：Monisha S R 2018-10-26

Hi Torsten, My vector is very long (like 4000 elements), so outputting to the command window and checking the values is a tedious process. But nevertheless I can try with a smaller number of nodes. Thanks.

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