Infintite Loop- bisection search how to stop

function rootx = bisectionSearch (fhandle,a,b,epsilon)
while (b-a) > epsilon %assume a<b
      m =(b+a)/2
    fhandlem=fhandle(m);
        if fhandlem == 0 
         rootx = m    %If f(m) is equal to zero then return the root as m
      else if sign (fhandle(m))== sign (fhandle(a)) % 
            a=m; % If f(m) has the same sign as f(a) Replace a with m 
             else  
                m=b;   
          end
        end 
end
m;
end
Hi guys this is an infinte loop and I do not know why or how to fix it Please help if possible. when I test it it keeps giving me m values repeatly of 1.75 and I dont think thats even the right answer. please Help!

[Matt J]

It gives you m=1.75 repeatedly with what input arguments?

[Michael Kurniawan]

[x]=bisectionSearch(f,1,2,0.01) f= @(x)sin(x)-log(x+1)

Answer 1

[Matt J]

In the case fhandlem==0, you should BREAK to terminate the loop. Also, you need b=m instead of m=b.

Finally, you could use an ELSEIF structure instead of ELSE...IF.

[Michael Kurniawan]

while (b-a) > epsilon %assume a<b
      m =(b+a)/2
    fhandlem=fhandle(m);
        if fhandlem == 0 
            break
         rootx = m    %If f(m) is equal to zero then return the root as m
      else if sign (fhandle(m))== sign (fhandle(a)) % 
            a=m; % If f(m) has the same sign as f(a) Replace a with m 
             else  
                m=b;   
          end
        end 
end
m;
end
Hello Matt Thank you for your help. Not sure if this is what you meant but I tried this and its still looping.

[Matt J]

You need b=m instead of m=b.

You also still haven't given us input data that we can use to reproduce the problem.

[Michael Kurniawan]

function rootx = bisectionSearch (fhandle,a,b,epsilon)
while (b-a) > epsilon %#ok<ALIGN> %assume a<b
      m =(b+a)/2
    fhandlem=fhandle(m);
        if fhandlem == 0 
            break
         rootx = m    %If f(m) is equal to zero then return the root as m
        elseif sign (fhandle(m))== sign (fhandle(a)) % 
            a=m; % If f(m) has the same sign as f(a) Replace a with m 
             else  
                m=b;   
          end
        end 
end
Hello Matt  is this what you wanted me to do

[Matt J]

No, never mind. Go back to your previous code and set b=m instead of m=b.

[Michael Kurniawan]

No matt you are right I did need to set b=m instead of m=b. The infinite has stopped now

[Michael Kurniawan]

Thank you!!

[Matt J]

Move rootx=m to the last line of the function.