Problem with ComplexExpand[Abs[]]

*To*: mathgroup at christensen.cybernetics.net*Subject*: [mg1807] Problem with ComplexExpand[Abs[]]*From*: Paul E Howland <PEHOWLAND at taz.dra.hmg.gb>*Date*: Thu, 17 Aug 1995 00:01:58 -0400

I'm posting this on behalf of a colleague of mine. He is running into a problem where ComplexExpand[Abs[a + I b + Sqrt[a + I b]]] will not evaluate further. What's going on? Is there a way to expand Sqrt[a + I b] into something of the form (d + I e) which Abs can cope with, or has he hit against some fundamental problem with complex algebra which says there is no general solution to this problem? Any help would be much appreciated. Paul E Howland Long Range Ground Radar Systems Section tel. +44 (0)1684 895767 LSC2 Division, Room BY209 fax. +44 (0)1684 896315 Defence Research Agency email: PEHOWLAND at DRA.HMG.GB Malvern, Worcs, WR14 3PS, UK. -----------------------------------------------------------------------------