Manipulating a complex modulus expression
- To: mathgroup at smc.vnet.net
- Subject: [mg82860] Manipulating a complex modulus expression
- From: carlos at Colorado.EDU
- Date: Thu, 1 Nov 2007 05:21:21 -0500 (EST)
Could somebody explain why Mathematica does not return the same expression in the following cases. Version: 5.2 on Mac OSX 10.4.9. Let d=(Abs[-1+x+I*y])^2; The following 3 statements should be equivalent, since the documentation says that ComplexExpand assumes that all variables are real: s=ComplexExpand[d]; Print[s]; s=Simplify[d,x=E2=88=88Reals&&y=E2=88=88Reals]; Print[s]; s=FullSimplify[d,x=E2=88=88Reals&&y=E2=88=88Reals]; Print[s]; All should return (-1+x)^2+y^2. But only the last one does. Make a slight change: d=1/(Abs[-1+x+I*y])^2; Now none of the 3 returns 1/ ((-1+x)^2+y^2) . Why?