loop while doesn't stop

Hi everybody,

I wrote a code related to a wind turbine exercice but my loop while does not stop and I don't understand why because it seems that stop conditions are fulfilled.

My loop while should stop when (a-a1=0) & (aprime-aprime1=0)

It would be great if you can have a look at my following code :

clear all

% Variable speed of the rotor

w=2.61;

% Air density 1.225 kg/m3

d=1.225;

% Rotor diameter 62 m

R=31;

% Number of blades 3

B=3;

% Cut in wind speed 5m/s
V0=15;

% local pitch
 theta=0;

r=24.5;
Betat=2;
c1=1.09

   erreur=1;
   a=0;
   aprime=0;
  a1=0;
  aprime1=0;
  compteur=0;
  while  erreur>1e-3
      compteur=compteur+1

        a=a1;
        aprime=aprime1;

      phi=atan((1-a)*V0/((1+aprime)*w*r));
      phi_deg=phi*180/pi;
      alpha=phi_deg-(theta+Betat);

      Cl=1;
      Cd=0.001;

      Cn=Cl*cos(phi)+Cd*sin(phi);
      Ct=Cl*sin(phi)-Cd*cos(phi);

      F=(2/pi)*acos(exp((-B/2)*(R-r)/(r*sin(phi))));

      sigma=c1*B/(2*pi*r);

      a=1/((4*(sin(phi))^2*F/(sigma*Cn))+1);

      aprime=1/((4*sin(phi)*cos(phi)*F/(sigma*Ct))-1);

       erreur=abs(abs(a-a1)+abs(aprime1-aprime));

      matrix(compteur,1)=a
      matrix(compteur,2)=aprime
      matrix(compteur,3)=alpha
      matrix(compteur,4)=phi_deg
      matrix(compteur,5)=Cn
      matrix(compteur,6)=Ct

end

Kind regards

[Jan]

Please use proper code formatting to improve the readability. Follow the "Markup help" link to learn the details.

See this link about avoiding CLEAR ALL:

http://www.mathworks.com/matlabcentral/answers/16484-good-programming-practice#answer_22301

[Andrei Bobrov]

so?

a1=1/((4*(sin(phi))^2*F/(sigma*Cn))+1);

Answer 1

[Jan]

Your code creates the same values in each iteration, because you initialize a to a1 and aprime to aprime1 repeatedly. Please use a debugger to check this: Set a breakpoint in the code and step through your program line by line.