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?

```

• Prev by Date: Re: library.wolfram submissions
• Next by Date: NDSolve with functions of vectors
• Previous by thread: Re: library.wolfram submissions
• Next by thread: Re: Manipulating a complex modulus expression