Author 
Comment/Response 
Frank

10/08/12 09:02am
Hello there,
Does anyone know why FullSimplify can't simplify Abs[1] and Abs[4] in the following nested expression?
FullSimplify[If[Log[S[Plus[x,x,x]]]==0,Log[Plus[Times[x,4],If[x==0,Rational[9,2],x],Plus[x,Rational[10,7]]]],Times[P[Abs[1],Abs[4]],P[x,Exp[Rational[5,4]]]]]]
This is what I get:
If[Log[S[3 x]]==0,Log[x 4+If[x==0,(9/2),x]+(x+10/7)],P[Abs[1],Abs[4]] P[x,Exp[(5/4)]]]
Instead I would expect the following result:
If[Log[S[3 x]]==0,Log[x 4+If[x==0,(9/2),x]+(x+10/7)],P[1,4] P[x,Exp[(5/4)]]]
Here S[_] and P[_,_] are my userdefined functions, but here they are only symbolic: I didn't defined them here before the simplification.
I also noticed that it works when the condition expression of the If instruction is without my userdefined function S. Do You know why?
Thanks in advance for your help.
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