MATLAB: Do while loop with recursive make the answer incorrect

recursivewhile loop

Dear all,
I have question about doing while loop since i try to find a value of h0 in while loop by using Newton's method and i let the 4 input parameters be recursive in the folowing(just want to recheck that's why i set N=2). And i also let it print the value of each parameters to recheck the value of h0.
function h0 = minftnaja
mmin = 3;
mmax = 12;
almin = 0.1;
almax = 1;
R0min = 0.013;
R0max = 0.015;
R1min = 0.020;
R1max = 0.050;
ita = 0.1;
 frad = 220;
 rpm = 20000;
 
 N = 2 ;
[m_, al_, R0_, R1_] = ndgrid( linspace(mmin, mmax, N), ...
    linspace(almin, almax, N), ...
    linspace(R0min, R0max, N), ...
    linspace(R1min, R1max, N));
h0 = 0.00002;
heps = 0.0001;
errF = 1e-4;
err = 1;
while all(err > errF) % will not stop as long as even one entry is out of tolerance,
                          % so when you stop then all of them will be within tolerance.
        
        k   =   pi .* (R0_ + R1_) .* tan(al_ .* pi ./ 180) ./ (m_ .* h0);
        fu  =   6 .* (R1_ - R0_) .*  (-rpm .* pi .* (R0_ + R1_) ./ 60) .* ita .* (-log(k+1) + ((2*k)./(k+2))) ./ (tan(al_ .* pi ./ 180)).^2; 
        f   =   fu-frad;
        h0  =   h0+heps;
        kk  =   pi .* (R0_ + R1_) .* tan(al_ .* pi ./ 180) ./ (m_ .* h0);
        fu  =   6 .* (R1_ - R0_) .*  (-rpm .* pi .* (R0_ + R1_) ./ 60) .* ita .* (-log(kk+1) + ((2*kk)./(kk+2))) ./ (tan(al_ .* pi ./ 180)).^2;
        f1  =   fu-frad;
        h0  =  h0-heps;
        
        
        
        jacobian = (f1-f)/heps;
        h0    = h0 - 0.01*f./jacobian;
        err = abs(f/frad);
        
        if err > errF
            
        else
            m_
            al_
            R0_
            R1_
            
        end
         
end
I use the value from each parameter to recheck the value of h0 by the function which is not using recursive to be input in the following.
 function h0 = GG
frad = 220; %loading
rpm = 20000;
m = 3;         %1
alpha = 0.1;   %2
R0 = 0.013;  %3
R1 = 0.020;  %4
 
ita=0.01; 
h0 = 0.00002;
heps = 0.0001; 
errF = 1e-4; 
err = 1;
    while all(err > errF)
        
        k   =  (2*pi*(R0+R1)/(2*m))*tan(alpha*pi/180)/h0;
        fu  =  -(6*ita*(rpm*2*pi*(R0+R1)/(2*60))*(R1-R0)*(2*pi*(R0+R1)/(2*m))^2)*(-log(k+1)+(2*k)/(k+2))/((k^2)*(h0^2));
        f   =  fu-frad;
        h0  =  h0+heps;
        kk  =  (2*pi*(R0+R1)/(2*m))*tan(alpha*pi/180)/h0;
        fu  =  -(6*ita*(rpm*2*pi*(R0+R1)/(2*60))*(R1-R0)*(2*pi*(R0+R1)/(2*m))^2)*(-log(kk+1)+(2*kk)/(kk+2))/((kk^2)*(h0^2));
        f1  =  fu-frad;
        h0  =  h0-heps;
       
        jacobian = (f1-f)/heps;
        h0    = h0 - 0.01*f/jacobian;    
        err = abs(f/frad);
       
    end
    
   
end
The result is not the same and i also recheck that is this h0 correct from while loop with recursive? by use the values of 4 parameters and h0 to find value of fu which should give the value approximately equal to frad but it is not.
So i just wonder may be because of doing recursive in while loop that's the reason why the result is not the same. Am i right??

Best Answer

Paranee - please clarify what recursive means to you. You may want to start with N equal to one and compare the results. If they are still different then ask yourself why. For example, should you get identical results when parameters such as alpha, ita, m, R0, R1, etc. are initialized to different values in your two functions? If they are the same then you will get identical results...
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