getting error with symengine

Below is my code, literally get the error and didnt find any solution, pls help me

syms u v x y z
F = @(x,y,z) log (x.^2-2.*y) - z;
x = @(u,v)u+v;
y = @(v)exp(v);

F = subs(F)
Error using symengine
Arithmetical expression expected.

Error in sym/subs>mupadsubs (line 160)
G = mupadmex('symobj::fullsubs',F.s,X2,Y2);

Error in sym/subs (line 145)
    G = mupadsubs(F,X,Y);

Error in subs (line 68)
    r_unique_name = subs(sym(f_unique_name),varargin{:});

[Tommy Lim]

i run this code in MATLAB r2014a, everthing fine... but when i switch to MATLAB r2020a, i get error

Answer 1

[Awais Saeed]

It is good to provide a variable list and expressions you want to replace using subs(). Read more about subs() here.

syms u v x y z
F = @(x,y,z) log (x.^2-2.*y) - z

F = function_handle with value:
    @(x,y,z)log(x.^2-2.*y)-z

old = {x,y}; % replace these with 'new' expressions
new = {@(u,v)u+v,@(v)exp(v)};
Fnew = subs(F, old, new)

Fnew = 

Answer 2

[Walter Roberson]

syms u v x y z

x(u,v) = u+v;
y(u,v) = exp(v);
F = log (x(u,v).^2-2.*y(u,v)) - z

F = 

This produces the same result as would have been produced before (I tested.)