function demo2_1b;
% the REALISTIC bisection method 
% solve f(x)=0 on [A,B]
%
eps=0.00001;
% initial interval for sin(x)
%A=1;
%B=4;
% initial interval for 3x-e^x
A=1;
B=2;
%
a=A;
b=B;
p=(a+b)/2;
%% set up a counter to count the number of iterations
i=1;
% MAIN LOOP 
if (f(a)*f(p))>0 & (f(a)*f(p))>0
 fprintf(1,'Error: no root in the given interval A: %6.2f B:%6.2f \n', A, B);
 a=b; p=[];
else
while (abs(f(p))>eps) & (abs(b-a)>eps) & (i < 100)
if (f(a)*f(p))<0 
   b=p;
end 
if (f(b)*f(p))<0  
   a=p;
end
p=(a+b)/2;
i=i+1;
end
%% To display all decimals, switch default print formatting to ''long''
format long 
%%%%%
fprintf(1,'Number of iterations: %1i Solution found: %10.8f \n', i, p);
% compare with the true solution for sin(x)
%pi
%abs(pi-p)
end

function y=f(x);
%y=sin(x);
y=1;