recognize function from string

Is there a way in Matlab to recognize the variables and parametest of function from sting. For example I have a string: "a1*x+a2*x^2+y", and necessary to get a function where a1,a2 - constants and x, y - variables.

Answer 1

[Star Strider]

Not that I am aware of.

The closest you can get to what you want to do (in this example of a polynomial) is the Symbolic Math Toolbox coeffs function, and even then you have tell it what the variables are:

syms a1 a2 x y 
z = a1*x+a2*x^2+y;
[coefficients,variables] = coeffs(z, [x y])

coefficients =
[ a2, a1, 1]

variables =
[ x^2, x, y]

[Zak Kankin]

Thanks! It works great for string in exactly if I want! '[coefficients,variables] = coeffs('a1*x+a2*x^2+y', [x y])'

coefficients = [ a2, a1, 1] variables = [ x^2, x, y]

[Star Strider]

My pleasure!