MATLAB: Is slow

slow

Hey guys, i'm trying to run this script but it takes too long. Can i change anything to make it faster?
Note: I've already tried in another computer.
a=1560;                            
b=6360;                    
tol=500;               
it= 50;
g=@(P)(3*10^7*(P^(-0.6)+7/P)+800*P^0.7+400000);
x1=a+(1/4)*((b-a)/4);
x2=a+(2/4)*((b-a)/4);
x3=a+(3/4)*((b-a)/4);
g_x1=g(x1);
g_x2=g(x2);
g_x3=g(x3);
while (abs(b-a)>tol) 
      if g_x1<g_x2
          b=x2;
          x2=x1;
          x1=a+(1/4)*((b-a)/4);
          g_x1=g(x1);
          g_x2=g(x2);
          g_x3=g(x3);
      elseif g_x3<g_x2
              a=x2;
              x2=x3;
              x3=a+(3/4)*((b-a)/4);
              g_x1=g(x1);
              g_x2=g(x2);
              g_x3=g(x3);
      else g_x3>g_x2
              a=x1;
              b=x2;
              g_x1=g(x1);
              g_x2=g(x2);
              g_x3=g(x3);
      end
end

Best Answer

The problem is not that your code is slow, but that your algorithm doesn't converge.
abs(b-a) reaches 1925.3906, and stays there, so the while loop doesn't end.
Related Question