The objective function for fsolve is currently not defined to take more than one input.
Historically, extra parameters in the fsolve call were added as arguments to the objective function. That syntax has been obsolete and undocumented since MATLAB 5.1 and might or might not work.
If it does work, then in your call
fsolve('derofexpexp2',finnoearth(finpeakh,1),options2a,[],eqdif,eqdf3,indexpl1,indexexp1);
the argument finnoearth(finpeakh,1) would correspond to x0, and the argument options2a would correspond to options, leaving [], eqdif, eqdf3, indexp11, and indexexp1 as extra arguments. That would be 5 extra arguments in addition to the x argument, which would lead to 6 arguments passed to the function. But your function is only defined to take 5 arguments.
Please read http://www.mathworks.com/help/matlab/math/parameterizing-functions.html . (Unless, of course, you are still using MATLAB 4.x, which would be pretty major information that you would have been expected to mention already.)
