Converting a string to an expression in MATLAB

Question

I'm writing a small MATLAB package and I'd like to ask for user input for a function. So if the user enters:

x.^2 + sin(x)

I want to use this user input to appear elsewhere in the code, but x would already be defined and so the expression above would be a vector (or scalar if length(x) is 1).

David Heffernan · Accepted Answer · 2013-05-24 09:32:25Z

4

You can use the eval function for this. For example:

>> x = 5

x =

     5

>> eval('x*3')

ans =

    15

answered May 24, 2013 at 9:32

David Heffernan

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Comments

Oleg · Accepted Answer · 2013-05-24 19:55:13Z

2

You can create a function handle:

% some variable you already defined
myVar = 5;

% Create an anonymous function in some z 
f = str2func('@(z) z.^2 + sin(z)');

% Call function supplying the input
f(myVar)

answered May 24, 2013 at 19:55

Oleg

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