Create a function from user input string

I am trying to develop a GUI which will allow the user to type a function into a text box and then perform operations to that function. For example suppose the user inputs 'x^2+2x+3' into a text box.

How can I convert the string into a function so I can perform iterative operations on?

such as:

function [y] = f(x)
 y=x^2+2x+3;
end

I am fairly new at matlab so any help would be appreciated.

Answer 1

[Fangjun Jiang]

>> str='x^2+2*x+3'
str =
x^2+2*x+3
>> f=inline(str)
f =
     Inline function:
     f(x) = x^2+2*x+3
>> f(2)
ans =
    11

[klement omeri]

Is there any other way to do this? I am doing it in the same way but matlab shows me a yellow warning that inline function will be removed in a future release.

[Stephen23]

@klement omeri: read the very first line of the inline help, which states "inline will be removed in a future release. Use Anonymous Functions instead." And then use an anonymous function, just like the documentation advises. For example (from the help):

>> str = '@(x)7*x-13';
>> fh = str2func(str);
>> fh(3)
ans =
     8

Answer 2

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/15450-convert-a-symbolic-equation-to-a-vector-equation