how take a mathematical function from user

How can i take F and G from the user to use them in a function if i have F=@(x,y) x./y;

and G=@(x) sqrt(x.^2+1); ?

[Dyuman Joshi]

You mean, you want the user to input x and y and get the F and G values?

[Jonas]

if you really want to be able to let the user enter matlab code (a function), then you may use feval().

[Ahmed Amin]

i mean that in my origina code it is me who wite the function F and G in File.m like that but i wnat the user to enter the F and G insted of me to use them in Function

[Ahmed Amin]

ok but how can i use feval in my case ?

Answer 1

[Steven Lord]

What do you mean when you say you want "the user to enter" the function in your comment?

Do you want the user to have to pass some thing into your function that lets your function call a function of their choosing? If so you want your user to define a function handle (which could be an anonymous function.)

f1 = @(x, y) x./y; % anonymous function
z1 = integral2(f1, 0, 1, 1, 2) % integral2 will call the function f with inputs of its choice

z1 = 0.3466

f2 = @sin; % regular function handle
z2 = integral(f2, 0, pi)

z2 = 2.0000

Or do you want to have the user enter the text of a function in say an edit box in a dialog or UI? In that case you should use str2func.

s = 'x./y';
f3 = str2func(['@(x, y)' s]); % make an anonymous function which is a function handle
z3 = integral2(f3, 0, 1, 1, 2)

z3 = 0.3466

% or
f4 = str2func('sin'); % make a regular function handle
z4 = integral(f4, 0, pi)

z4 = 2.0000

Or did you have a different meaning in mind? In this case, please explain what you want to do in more detail.