MATLAB: Do I obtain a “Divide by zero” error when I set low tolerance values in LSQCURVEFIT in Optimization Toolbox 3.1 (R2006b)

Optimization Toolbox

I am getting a "Divide by zero" error when I set low tolerance values in LSQCURVEFIT. This happens when I run the following code:
function test() 
% test data 
data = [10 5 2 1]; 
t = [1 2 3 4]; 
% initial guess 
A0 = [10 1]; 
options = optimset('TolFun',1e-27,'TolX',1e-27, ...
      'MaxIter', 5000,'MaxFunEvals',50000, 'display', 'iter'); 
A = lsqcurvefit(@myfunc,A0,t,data,[],[],options); 
% fitting function 
function f = myfunc(A,t) 
f = A(1)*exp(-A(2)*t);
The exact error message is:
 Warning: Divide by zero.
 > In optim\private\trust>seceqn at 128
   In optim\private\trust>rfzero at 193
   In optim\private\trust at 55
   In optim\private\trdog at 228
   In optim\private\snls at 393
   In optim\private\lsqncommon at 213
   In lsqcurvefit at 182
   In test at 14

Best Answer

This issue has been fixed in MATLAB 7.4 (R2007a). For previous releases, use the following command before you run the optimization:
warning('off', 'MATLAB:divideByZero')
Related Question