RE: Bug in parsing expression?
- To: mathgroup at smc.vnet.net
- Subject: [mg49120] RE: [mg49062] Bug in parsing expression?
- From: "Wolf, Hartmut" <Hartmut.Wolf at t-systems.com>
- Date: Fri, 2 Jul 2004 02:01:20 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
>-----Original Message----- >From: Arturas Acus [mailto:acus at itpa.lt] To: mathgroup at smc.vnet.net >Sent: Wednesday, June 30, 2004 11:34 AM >To: mathgroup at smc.vnet.net >Subject: [mg49120] [mg49062] Bug in parsing expression? > > >Dear Group, > >Just try to evaluate this expression > >1/(5*(-7 + 4*Sqrt[3])^3*(1/2 - 1/(2*(-7 + 4*Sqrt[3])^2))*(((-384 + >224*Sqrt[3])*(3/2 + 2*Sqrt[3] + 1/(2*(-7 + 4*Sqrt[3]))))/(-1/2 + >1/(2*(-7 + 4*Sqrt[3])^2)))^(3/2)) > >in 5.0. on linux box I receive $IterationLimit::"itlim" message. >Is it repeatable? > >Sincerely. Arturas Acus > > Certainly not a parsing error, but apparently an infinite loop at simplifying. Help Mathematica to avoid this: In[1]:= 1/(5*(-7 + 4*Sqrt[3])^3*(1/2 - 1/(2*(-7 + 4*Sqrt[3])^2))*(((-384 + 224*Sqrt[3])*(3/2 + 2*Sqrt[3] + 1/(2*(-7 + 4*Sqrt[3]))))/(-1/2 + 1/(2*(-7 + 4*Sqrt[3])^2)))^(3/2)) >From In[1]:= $IterationLimit::"itlim": "Iteration limit of 4096 exceeded." In[2]:= Short[%1 // FullForm, 4] Out[2]//Short= Hold[Times[Rational[1, 5], Power[Plus[-7, Times[4, Power[3, Rational[1, 2]]]], -3], Power[\[LeftSkeleton]1\[RightSkeleton]], Power[\[LeftSkeleton]1\[RightSkeleton]]]] In[4]:= Replace[%1, Hold[Times[f1_, f2_, f3_, f4_]] :> Times @@ Simplify /@ {f1, f2, f3, f4}] // FullSimplify Out[4]= (I*(-12 + 7*Sqrt[3]))/(3840*(7 - 4*Sqrt[3])^6) In[12]:= %4 // N Out[12]= 0. + 236.43125000085212*I -- Hartmut Wolf