While loop doesn't continue looping!

Hey everyone,

In my code for estimating the root using bisection method, while loop only outputs one iteration! yy is user defined function for which the root will be estimated, Xl is the lower bound of the interval (user-defined), Xu is the upper bound of the interval (user-defined), imax is the max number of iterations, I use a function fun to convert the symbolic function into numerical

function [iter, Xr, ea] = Bisect(yy, Xl ,Xu ,es ,imax, iter)
while iter <= imax || ea <= es

    if (fun(yy,Xl) * fun(yy,Xu)) < 0 %Verify that the interval [Xl,Xu] contains at least one root by examining the sign
        Xr = (Xl + Xu)/2;
        if (fun(yy,Xr) * fun(yy,Xl)) < 0
            ea = abs((Xr - Xu)/Xr)*100;
            Xu = Xr;
        else
            ea = abs((Xr - Xl)/Xr)*100;
            Xl = Xr;
        end
       break
    elseif fun(yy,Xl) == 0 
        Xr = Xl;
        ea = 0;
       break
    elseif fun(yy,Xu) == 0 
        Xr = Xu;
        ea = 0;
       break
    elseif (fun(yy,Xl)*fun(yy,Xu)) > 0
        disp('ERROR!! Please specify another upper and lower bounds for the interval on which a root might exist.')
       break
    end 

 end

iter = iter + 1; %Update the number of iterations

Answer 1

[Naty S]

Use continue instead of break. But i don't think you really need all those breaks or continues. Try without them. and in the elseif, you should change it from elseif fun(yy,xu)==0 to elseif fun(yy,xu)<Epsilon