constantly receiving an error undefined function or variable z when use solve

I was trying to find the intersection points of these function

f1=sym('y=x^3');

f2=sym('x^2+y^2=1');

S=solve(f1,f2,x,y);

solx=eval(S.x);

soly=eval(S.y);

I can't do eval(S.x) because i receive the error

Undefined function or variable 'z'.

[Stephen23]

Do not use eval on symbolic expressions:

https://www.mathworks.com/matlabcentral/answers/56166-symbolic-computaion-of-complex-number-and-using-eval-function-doesnot#answer_68084

https://www.mathworks.com/matlabcentral/answers/376032-using-eval-undefined-function-or-variable#answer_299055

https://www.mathworks.com/matlabcentral/answers/368517-how-do-you-use-the-function-eval#comment_507714

https://www.mathworks.com/matlabcentral/answers/400718-need-help-with-vector-and-eval#comment_568074

Answer 1

[Fabio Freschi]

Polynomials with a degree greater than 4 do not have explicit solutions. You can use vpa

syms x y
f1 = y == x^3
f2 = x^2+y^2==1;
S = solve([f1, f2],x,y);
vpa(S.x)
vpa(S.y)

Or double if you accept a double result

double(S.x)
double(S.y)