the equivalence between fit and cftool when fitting exp1 type curve

Dear Sir/Madam,

I am trying to fit a segment of my signal with an exp1 type curve. When I am trying it using fit command in matlab it is throwing an error. When I am trying to fit the same segment using cftool command, it is however executing in a nice manner. When I tried to look for the source of difference, I found out that the cftool is calculating an optimized starting values for the parameters a and b, while the fit command is not taking any such starting points. Is there any function available in MATLAB ommand line which will help me find the optimized starting points?

Please let me know. My research is stuck at a point due to this issue.

Regards,

Aditi Misra