Re: problem to define a complex variable

*To*: mathgroup at smc.vnet.net*Subject*: [mg116676] Re: problem to define a complex variable*From*: Daniel Lichtblau <danl at wolfram.com>*Date*: Wed, 23 Feb 2011 05:26:44 -0500 (EST)

tarun dutta wrote: > i want to use complex variable such as > c[i_]=re[i]+I*im[i] > then I get > conj[c[i]] =re[i]-I*im[i] > by stating > conj[a_]:=complexexpand[conjugate[a]]; > but now i am writing > c[i_][t_]=re[i][t]+I*im[i][t] > but i am not getting > conj[c[i][t]]=re[i][t]-I*im[i][t] > by stating > conj[a_]:=ComplexExpand[Conjugate[a[i][t]]] > > is there any way of writing this thing? > any help will be very much appreciated. > regards, > tarun The result below looks about right to me. In[327]:= c[i_][t_] := re[i][t] + I*im[i][t] conj[a_] := ComplexExpand[Conjugate[a]] In[329]:= conj[c[i][t]] Out[329]= -I im[i][t] + re[i][t] This was in version 8. A bug in earlier versions caused the various entities to be regarded as "complex valued". So you would see something like below. By the way, it would save people like myself a lot of time if you actually show your input and output, so nobody has to guess at the nature of teh problem. Out[4]= -Im[im[i][t]] + I (-Im[re[i][t]] - Re[im[i][t]]) + Re[re[i][t]] To work around this I'd suggest postprocessing with Simplify, giving assumptions that re[i][t] and im[i][t] are both real valued. Daniel Lichtblau Wolfram Research