Re: Limit[(x - Log[Cosh[x]]) SinIntegral[x], x -> Infinity]

*To*: mathgroup at smc.vnet.net*Subject*: [mg86947] Re: Limit[(x - Log[Cosh[x]]) SinIntegral[x], x -> Infinity]*From*: "Szabolcs HorvÃt" <szhorvat at gmail.com>*Date*: Thu, 27 Mar 2008 08:16:21 -0500 (EST)*References*: <20080326082007.401$ci@newsreader.com>

On Wed, Mar 26, 2008 at 1:20 PM, David W. Cantrell <DWCantrell at sigmaxi.net> wrote: > I confirm the precise behavior you described. It's surprising that a > restart was required. Actually a ClearSystemCache[] is enough, but since cached results can affect the success of calculations, probably it would be better if Mathematica did not cache the "result" that it *cannot* calculate something. > > In[4]:= ClearSystemCache[] > > In[5]:= Limit[(x - Log[Cosh[x]]) SinIntegral[x], x -> Infinity] > > Out[5]= Limit[(x - Log[Cosh[x]]) SinIntegral[x], x -> Infinity] > > In[6]:= Limit[FullSimplify[(x - Log[Cosh[x]]) SinIntegral[x], x > 0], > x -> Infinity] > > Out[6]= (1/2)*Pi*Log[2] > > Note that using FullSimplify merely changes -Log[Cosh[x]] to +Log[Sech[x]], > but curiously, that seems to help. Hmm, this does not work for me: In[1]:= Limit[FullSimplify[(x - Log[Cosh[x]])*SinIntegral[x], x > 0], x -> Infinity] Out[1]= Limit[(x + Log[Sech[x]])*SinIntegral[x], x -> Infinity] I get back the same expression even if I evaluate all 6 input cells in turn. In[2]:= $Version Out[2]= "6.0 for Microsoft Windows (32-bit) (February 7, 2008)" Szabolcs

**Follow-Ups**:**Re: Re: Limit[(x - Log[Cosh ]) SinIntegral , x -> Infinity]***From:*Daniel Lichtblau <danl@wolfram.com>