clear all  % clear all variables 
close all  % close all figures

x=-10:0.1:10;
y=exp(x)-tan(x);
plot(x,y)

xr=-2.8;  % initial right boundary
xl=-4;    % initial left boundary

for j=1:1000  % j cuts the interval
   
    xc=(xl+xr)/2;  % calculate the midpoint
    fc=exp(xc)-tan(xc);  % calculate function
    
    if fc>0
        xl=xc;  % move left boundary
    else 
        xr=xc;  % move right boundary
    end
    
    if abs(fc)<10^(-5)
        break   % quit the loop
    end
    
end

xc   % print value of root
fc   % print value of function