How to insert a function into a GUI

Hi.

I'm making a simple GUI which receives functions and do operations on them. It is complete, however to change the function I need to modify the code and change the function.

Is there anyway to insert a funcion into a GUI as a string and converting it into a function?

e.g: the user inserts x.^2+x

The code receives it as string and converts it to a variable so that

y = x.^2 + x (the x will be defined beforehand)

Thanks in advance. I hope I've expressed my doubt clearly enough. Daniel.

Answer 1

[Image Analyst]

Yes, just go ahead and enter it in any place that is not another function. For example at the very end of your code, add this

function y = MyPolynomial(polynomialString, x)
  coefficients = ParseString(polynomialString)
  y = coefficients(1) * x^2 + coefficients(2) * x + coefficients(3);

function coefficients = ParseString(polynomialString)
  equalsLocations = findstr(polynomialString, '=');
  plusLocations = findstr(polynomialString, '+');
  minusLocations = findstr(polynomialString, '-');
  % etc.  You do the rest.

[Daniel Jaló]

Thanks for the answer, but that won't allow me to insert any function at will, only a second degree polinomial function. I gave the function as an example, my objective is to be able to convert any function I insert.

Thanks. Daniel

Answer 2

[Walter Roberson]

y = str2func(['@(x) ', TheString]);