help with editing variables

Hello, a=2; b=a+3 How to modify the constant "a" after I declare this constant, to modify the variable b?

Answer 1

[Andrei Bobrov]

f1 = @(a)a + 3
b = f1(a)

Answer 2

[Daniel Shub]

While there are ways to do this (e.g., functions, function handles and handle classes), this is not really how MATLAB works. In MATLAB expressions become variables, which are constants, as soon as you evaluate the expression (i.e., press enter or run you script). This means that

clear x y
z = x+y;

gives an error since x and y are not defined (I cleared them).

x = 1;
y = 2;
z = x+y;

z
x = 10;
z

returns 3 in both cases since z loses its dependence on x and y as soon as it is evaluated.