Is it overflow?how can I input 2.5e-6?

[John D'Errico]

Moved answer by @Shaonong Wei into a comment.

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Answer 1

[Ameer Hamza]

This happens because of the way MATLAB parses the expression vpa(2.5e-6). First, MATLAB converts 2.5e-6 into a double datatype, and due to the finite precision of double(), you don't exactly get 2.5e-6. And only after that, MATLAB converts it to symbolic. In the second case, 2.5e-5 can be exactly represented, and thus, the problem does not occur. The workaround is to pass the 2.5e-6 as a char array

vpa('2.5e-6')