Скачать или смотреть How to Fix the LSODE Error: "INTDY-- T (=R1) ILLEGAL and Invalid Input Detected" in MATLAB

Learn how to resolve the `INTDY-- T (=R1) ILLEGAL` error encountered while using `lsode` in MATLAB by ensuring your time points are monotonous.
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Understanding the INTDY-- T (=R1) ILLEGAL Error in MATLAB

Are you encountering the frustrating INTDY-- T (=R1) ILLEGAL and invalid input detected error while trying to use the lsode function in MATLAB? This problem typically arises when the time points specified in the simulation are not in the correct format. Specifically, the time points must form a monotonous array, meaning they should be sorted in ascending order. In this guide, we will delve deep into this error and provide you with a clear, step-by-step solution to address it.

Understanding the Problem

When simulating systems of differential equations with MATLAB's lsode function, users often define time points over which they want to compute solutions. In the user's case, they had a function defined as follows:

[[See Video to Reveal this Text or Code Snippet]]

They attempted to run lsode with the following command:

[[See Video to Reveal this Text or Code Snippet]]

However, an error message was generated, indicating an illegal time point in the input array.

Key Details of the Error Message

The error specifies that the time value R1 is not within the interval defined by the current time TCUR and step size HU. This common issue usually stems from the vector of time points being non-monotonous (not sorted).

The Solution: Sort Your Time Points

The solution to this problem is straightforward: ensure that your t_points array is monotonously increasing. Here’s how you can implement this fix in your code.

Step 1: Modify Your Code

Before executing your lsode function, simply sort your time points with the sort function. Here’s how you can adjust your code:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Rerun Your Simulation

After implementing the sorting step, rerun your simulation command. This should resolve the INTDY-- T (=R1) ILLEGAL error, allowing lsode to process the sorted time points correctly.

Conclusion

In summary, the error you encountered is often due to improperly formatted time points in your array. By ensuring that your array of time points is monotonous using the sort function, you can successfully run your lsode simulations without further issues. We hope this guide provides clarity and aids in your future MATLAB programming endeavors!

If you have any further questions or run into any additional challenges, feel free to leave a comment below. Happy coding!