Converting string to function/number

조회 수: 15 (최근 30일)
Luqman Hadiwinata
Luqman Hadiwinata 2022년 5월 26일
댓글: Luqman Hadiwinata 2022년 6월 2일
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?
  댓글 수: 2
Stephen23
Stephen23 2022년 5월 27일
편집: Stephen23 2022년 5월 27일
"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 2022년 6월 2일
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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답변 (3개)

Rik
Rik 2022년 5월 26일
The way to avoid eval in this case is to use str2func:
f=str2func('cos');
f(pi)
ans = -1

David Hill
David Hill 2022년 5월 26일
Look at eval function (normally not recommended).
a='cos(1)';
eval(a)

Walter Roberson
Walter Roberson 2022년 5월 27일
str2sym()
matlabFunction is commonly used together with str2sym()

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