Help with NMaximize

*To*: mathgroup at smc.vnet.net*Subject*: [mg101235] Help with NMaximize*From*: K Zhang <kezhao.zhang at gmail.com>*Date*: Sat, 27 Jun 2009 06:05:30 -0400 (EDT)

I was trying to minimize a function with one variable. I used NMaximize with various methods but none gave the correct answer. I can plot the objective function in In[3] and the maximum is located at around x=8.6. It appears that the variable x in the objective function is not evaluated in the function Count during the numerical optimization. In[1]:=SeedRandom[1] In[2]:=z = RandomReal[{5, 20}, 10] Out[2]:={17.2608, 6.67129, 16.8429, 7.81705, 8.62041, 5.98608, 13.1337, \ 8.46732, 10.9401, 15.5071} In[3]:=NMaximize[Count[z, _?(# < x &)]/x + Count[z, _?(# >= x &)]/Max [z], x, Method -> "SimulatedAnnealing"] Out[3]:={0., {x -> 2.71773}} I would appreciate any help to find the maximum point. Thanks. K. Zhang