syms to another .m file

How do you export your syms equation to a new/different .m file to be able to use the equation with parameters.

Answer 1

[Walter Roberson]

As @Torsten says, you can just pass symbolic expressions as parameters.

However, you need to be careful about assumptions. All levels of MATLAB code share the same assumptions, and using syms on a variable resets assumptions.

syms x positive
assumptions

ans = 

f = sin(x)+x^2

f = 

testit(f, x)

ans = 

 
ans =
 
Empty sym: 1-by-0
 

ans = 

ans = 

assumptions

 
ans =
 
Empty sym: 1-by-0
 

function testit(f, var)
  assumptions
  syms x
  assumptions
  diff(f, x)
  diff(f, var)
end

Answer 2

[Torsten]

Call the other .m-file with the syms-equation (or function) as input argument.

syms x
f = x.^2;
result = fun(f)

result = 

4

function result = fun(f)
  syms x
  result = subs(f,x,2);
end