num_meth

syms x y;
syms f1(x, y);
syms f2(x, y);
syms f3(x, y);

f1=4*x+2*y-1;
f2=10*y-3;
f3=x+3*y+4;

T=[4 0 1; 2 10 3; -1 -3 4];
D=diag(diag(T));
U=(triu(T,1));
L=(tril(T,-1));

A=-D/(L+U);
g=D/b;
%%A=
%%g=

i=1;
x=[Inf,Inf,Inf];