Complex bessel function

*To*: mathgroup at smc.vnet.net*Subject*: [mg75167] Complex bessel function*From*: "Grasley, Zachary" <zgrasley at civil.tamu.edu>*Date*: Thu, 19 Apr 2007 04:31:01 -0400 (EDT)

I am currently trying to isolate the real and imaginary components of first and second order modified Bessel functions. For example, I have a function expressed as F=BesselI[0,sqrt(i)*a+b], where i is the imaginary unit. Both a and b are positive real. I need to separate out the real and imaginary components of F symbolically. I have tried Re, Im, ComplexExpand, I have used Assuming to define a and b as real and 0<a<infinity and 0<b<infinity. I have tried ComplexExpand. I have tried Refine[Im[F]]. I loaded the package ReIm. All of these functions do a fine job separating the real and imaginary components when I provide numeric values for a and b, but are unable to solve symbolically. I thought Refine was supposed to solve symbolically as if a numeric value has been assigned to the variables (with the value range of the variable defined by Assuming or the assumptions listed in Refine)? Am I missing some simple trick to solve this symbolically, or is this not possible? Thanks in advance! Zach