How do I use an additional variable on a quadl function in Matlab?

Question

I am trying to pass a function from another .m file into a quadl call that also takes an extra variable when evaluating the function.

My current call looks like:

fun=@fun1
min = 0;
max = 2;
y=quadl(fun, min, max, 0.00001);

I want to have fun1 to be evaluated from min to max.

My function in the fun1.m file is:

function func=fun1(x)
    func = x^2+x+y

How do I pass the 'y' variable in?

I have tried to change the quad call to:

y=quadl(fun1(y), min, max, 0.00001);

and:

y=quadl(fun1(y), min, max, 0.00001);

and the function to:

function func=fun1(x,y)
    func = x^2+x+y

but that does not work.

I have also tried declaring a global variable but it is giving me an undeclared variable error.

Help is appreciated!

Answer 1

First of all quadl will be removed in future releases, so it's best to use integral.

You should use:

function func=fun1(x,y)
    func = x.^2+x+y;         % with .^

Then in your other script, you declare fun as a function of x:

y = 5;
fun=@(x)fun1(x,y);
min = 0;
max = 2;
y=integral(fun, min, max);

If you insist on using quadl, you can do exactly the same:

y = 5;
fun=@(x)fun1(x,y);
min = 0;
max = 2;
y=quadl(fun, min, max, 0.00001);

---

EDIT: To keep an expression in function of y aft er the integration of x, you need to work with syms and int:

syms x y z
fun = fun1(x,y,z);
min = 0;
max = 2;
expr = int(fun,  x, min, max);