How can I make the name of symbolic variable same with the parameter? or Can I make symbolic variable as global?

example, x = sym('x'), y = sym('y'). I found this way, syms('x'). then, symbolic variable 'x' is in the workspace. but I need to make symbolic variable in the function and use it in the main. So, I think that I need to make it as global. but, the way of syms('parameter'), I don't know how to make it...

help me, please.

thank you