Re: Re: Imaginary ...

*To*: mathgroup at smc.vnet.net*Subject*: [mg2529] Re: [mg2490] Re: [mg2430] Imaginary ...*From*: Allan Hayes <hay at haystack.demon.co.uk>*Date*: Thu, 16 Nov 1995 01:46:17 -0500

Jesus ROJO <jesroj at wmatem.eis.uva.es> in [mg2490] Re: [mg2430] Imaginary ... warns about f:=a+I b Sqrt[f*Conjugate[f]]//ComplexExpand Sqrt[(a+I b) Conjugate[a+I b]] I have recently been dealing with this laziness of ComplexExpand on some quite large expressions. The following might be of interest ComplexExpand[Sqrt[f*Conjugate[f]],TargetFunctions ->{Re,Im}] Sqrt[(a - I b) (a + I b)] Repeat: ComplexExpand[%,TargetFunctions ->{Re,Im}] 2 2 Sqrt[a + b ] So I used FixedPoint to automate the process FixedPoint[ ComplexExpand[#, TargetFunctions ->{Re,Im}]&, Sqrt[f Conjugate[f]] ] 2 2 Sqrt[a + b ] Allan Hayes hay at haystack.demon.co.uk