Converting string to function/number

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Luqman Hadiwinata
Luqman Hadiwinata 2022-5-26
评论： Luqman Hadiwinata 2022-6-2
Hello, sorry to bother your time. So in this case, my problem is, i'm trying to design an app using app designer that can take user input in string and convert it into numbers. However, when i try to use some mathematical function like 'sin, cos, exp' etc, as an input, i want those strings to be converted into the mathematical function as they were stated. How can i achieve this?
  2 个评论
Stephen23
Stephen23 2022-5-27
编辑：Stephen23 2022-5-27
"How can i achieve this?"
If you are interested in writing debuggable, robust, secure code and have only a limited number of such functions then use SWITCH or a cell array of explicit function handles or similar.
If you are happy with the risks of allowing the user to be able to run anything then use STR2FUNC.
Luqman Hadiwinata
Luqman Hadiwinata 2022-6-2
Hi Stephen, thank you for your answer. However i still have 1 question, if i want to add a time domain to my function, like:
t = 0:10:20000
rt = exp(t/10000).*cos(pi*t/500)
how can i achive this? by the way, thank you again for your answer

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回答（3 个）

Rik
Rik 2022-5-26
Ran in:
The way to avoid eval in this case is to use str2func:
f=str2func('cos');
f(pi)
ans = -1
David Hill
David Hill 2022-5-26
Look at eval function (normally not recommended).
a='cos(1)';
eval(a)
Walter Roberson
Walter Roberson 2022-5-27
str2sym()
matlabFunction is commonly used together with str2sym()

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