Why am I not able to find a solution using the bisection search i have implemented ?

i am trying to implement bisection search. the code is given below with all values. But i cannot find solution or the root for this. my phi, lambda values are precalculated. even if i change my phi, lambda values it still won't work. i want my bisection search to work, please guide me

% bisection search 
clc;
clear;

phi=[0.0002 - 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i   
   0.0000 - 0.0000i   0.0000 + 0.0000i  -0.0000 + 0.0000i 
   0.0000 - 0.0000i  -0.0000 - 0.0000i   0.0000 - 0.0000i  ];

lambda=[0.0000 - 0.0000i   0.0000 + 0.0000i   0.0000 + 0.0000i
   0.0000 + 0.0000i   0.0602 + 0.0000i   0.0000 + 0.0000i  
   0.0000 + 0.0000i   0.0000 + 0.0000i   0.0000 - 0.0000i   ];% 1.0e-03 *lambda

power=316.2278; % in watts
mu_array=[];

a=0.0001;      %mu1  % chosen arbitrary 
b=10;          %mu2  %chosen arbitrary
TOL=0.0001;     %tolerance value 
max_itr=100;   %max iterations
itr=0;         %iterations 

              
c=(a+b)/2;     


result3=muh_function(phi,lambda,c,power);
            
if result3==0 
    mu_array=[mu_array c];
else
    while abs(result3)>TOL && itr<=max_itr

           result3=muh_function(phi,lambda,c,power);
           result1=muh_function(phi,lambda,a,power);
           result2=muh_function(phi,lambda,b,power);
             
           if sign(result3)==sign(result1)
                   a=c;
                   b=b;
           else 
                   b=c;
                   a=a;
           end
                      

           c=(a+b)/2;
           itr=itr+1;
     end
    
end


function result=muh_function(phi,lambda,muh,power)
         M=2;
         sum=0;
         for m=1:M
             sum=sum+(phi(m,m)/(lambda(m,m)+muh)^2);
         end
         result=sum-power;    
end