function [x, iter] = bjt(x0,G)
F = zeros(5,1) ;
J = zeros(5,5) ;
VT = 25.3*exp(-3);
BF = 100;
BR = 1;
Is = 1*exp(-16);
i = 1;
x = x0;
while (norm(F,inf)>(1*exp(-9)))|(i==1)
F = G*x;
F(5) = F(5)-12 ;
J = G;
ID1 = (Is/BR)*((exp(x(1)-x(2))/VT)-1);
F(1) = F(1)+ID1;
F(2) = F(2)-ID1;
J(1,1) = J(1,1) + (Is/(BR*VT))*(exp(x(1)-x(2))/VT);
J(1,2) = J(1,2) - (Is/(BR*VT))*(exp(x(1)-x(2))/VT);
J(2,1) = J(2,1) - (Is/(BR*VT))*(exp(x(1)-x(2))/VT);
J(2,2) = J(2,2) + (Is/(BR*VT))*(exp(x(1)-x(2))/VT);
ID2 = (Is/BF)*((exp(x(1)-x(3))/VT)-1);
F(1) = F(1)+ID2;
F(3) = F(3)-ID2;
J(1,1) = J(1,1) + (Is/(BF*VT))*(exp(x(1)-x(3))/VT);
J(1,3) = J(1,3) - (Is/(BF*VT))*(exp(x(1)-x(3))/VT);
J(3,1) = J(3,1) - (Is/(BF*VT))*(exp(x(1)-x(3))/VT);
J(3,3) = J(3,2) + (Is/(BF*VT))*(exp(x(1)-x(3))/VT);
I0 = Is*(exp((x(1)-x(3))/VT) - exp((x(1)-x(2))/VT));
F(2) = F(2) + I0;
F(3) = F(3) - I0;
y = (-J)\F;
x = x+y;
i = i+1;
end
iter = i-1;
Vcc = 12;
r1 = 8000;
r2 = 4000;
re = 3300;
rc = 6000;
G = [((1/r1)+(1/r2)), (1/r2), 0, (-1/r1), 0;...
0, (1/rc), 0, (-1/rc), 0;...
0, 0, (1/re), 0, 0;...
0, (-1/rc), 0, (1/rc), 1;...
0, 0, 0, 1, 0];
x0 = [4; 6; 3.3; 12; -0.002];
[x, iter] = bjt(x0,G);
end
