Must be a text scalar when using eval() function problems?

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Ryan 2022-9-28

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https://ww2.mathworks.cn/matlabcentral/answers/1813360-must-be-a-text-scalar-when-using-eval-function-problems

回答： Walter Roberson 2022-9-28

n_stress = F./(t.*w);
n_stress = eval(n_stress);
Error using eval
Must be a text scalar.
Error in Carbon90 (line 55)
n_stress = eval(n_stress);

I am unsure as to why I am having issues using the eval() function with a something(underscore)something as the argument because I have not had this problem before.

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Answer 1

Walter Roberson 2022-9-28

1
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https://ww2.mathworks.cn/matlabcentral/answers/1813360-must-be-a-text-scalar-when-using-eval-function-problems#answer_1062035

eval() is defined only for character vectors and string scalars. It is not defined for numeric values, and it is not defined for symbolic expressions.

If you have a symbolic expression that does not have any unbound variables then you should double() the expression. If it has unbound variables then vpa() the expression.