Converting string to function/number

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?

[Stephen23]

"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]

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

Answer 1

[Rik]

The way to avoid eval in this case is to use str2func:

f=str2func('cos');
f(pi)

ans = -1

Answer 2

[David Hill]

Look at eval function (normally not recommended).

a='cos(1)';
eval(a)

Answer 3

[Walter Roberson]

str2sym()

matlabFunction is commonly used together with str2sym()