Re: Minimize with complex values

*To*: mathgroup at smc.vnet.net*Subject*: [mg91487] Re: Minimize with complex values*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Sat, 23 Aug 2008 01:43:30 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <g8lpel$imm$1@smc.vnet.net>

shama shahbaz wrote: > i want to minimize the absolute value of the following expression how ca= > n i do this in methamatica > > [exp(pi/4) +exp(3*pi/4)*exp(jp)]+[exp(pi/4) *exp(-5*pi*/4)]+[exp(3*pi/4= > )*exp(-3*pi*j/4)exp(jp)]+ > > [exp(pi/4) *exp(-10*pi*j/4)]+[exp(pi/4) *exp(-3*pi*j/2)exp(jp)]+[exp(pi= > /4)*exp(-15*pi*j/4)]+ > > [exp(3*pi/4)*exp(-9*pi*j/4)exp(jp)] > > p is the unknown value ,and it represent the phase...which is other than 0 = > ......is there any way to calculate it. > Regards=0A=0A=0A Say that "expr" holds your expression (written in correct Mathematica syntax), then you could use *NMinimize[]*. Note that you can also add constraint on the variable p. In[2]:= NMinimize[Abs[expr], p] Out[2]= {12.6907, {p -> -2.43096}} In[3]:= expr /. %[[2]] Out[3]= -12.512 + 2.12222 I In[4]:= NMinimize[{Abs[expr], 0 < p < 2 Pi}, p] Out[4]= {12.6907, {p -> 3.85222}} In[5]:= expr /. %[[2]] Out[5]= -12.512 + 2.12222 I Regards, -- Jean-Marc