MATLAB: How to make MatLab output unassigned variables

Question

I'm used to Mathematica, so I'm not sure how and if the same works with MatLab. Is there a way to input something like:

x = 3t

and have x be equal to 3t until you assign t a value?

edit:

so I have this code:

function [zr,w,R,q,mat] = test(z)  
lambda = 1;
w0 = 1;  
zr = (pi*w0^2)/lambda;
w = w0*sqrt(1+(z/zr)^2);
R = z + zr^2/z;
q = z + 1i*zr;
mat = [1 z; 0 1];  
end

but I not want to have to assign lambda and w0, i want them to just stay lambda and w0 UNLESS I assign them … so inputting

[zr,w,R,q,mat] = test(z)

should return the variables exactly how they look inside the function:

zr = 
      (pi*w0^2)/lambda
w = 
      w0*sqrt(1+(z/zr)^2)
R = 
      z + zr^2/z
q = 
      z + 1i*zr
mat = 
      1 z
      0 1

also, how come these don't exist outside of the function? I can't call q anymore for example after executing test because it doesn't appear to exist anymore

Answer 1

If I remember correctly, Mathematica is primarily a symbolic language. The most direct way to emulate Mathematica in MATLAB is to use the MATLAB Symbolic Math Toolbox.

For example:

syms x(t) 
x(t) = 3*t;
xt = x(t)
t = 9;
xt = x(t)

produces:

xt =   
3*t
xt =   
27