function s(x0, y0, TC)
if nargin<3; x0 = 0; y0 = 0; TC = 10^(-20);
end
syms x;
syms y;
f1 = @(x, y)(((0.20)*(exp( -2 * x) - (9*sin(x*y)))) - 0.4325);
f2 = @(x, y)(((0.20)*((x^2)*y) + (9*cos(x))) - 0.0643);
fd = diff(f1, x);
fd2 = diff(f1, y);
fd3 = diff(f2, x);
fd4 = diff(f2, y);
i = 0;
error = 100;
fk = [fd fd2 ; fd3, fd4];
c = [x(i+2) ; y(i+2)];
d = [x(i+1) ; y(i+1)];
x(1) = x0;
y(1) = y0;
while(error>TC)
    fu = inv(fk);
    fl = [(feval(f1, x(i+1), y(i+1))); (feval(f2, x(i+1), y(i+1)))];
    c = d -(fu * fl);
    A(1,1) = abs((x(i+2) - x(i+1))/ x(i+2)) * 100;
    A(1,2) = abs((y(i+2) - y(i+1))/ y(i+2)) * 100;
    error = max(A);
    i = i+1;
end