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

• To: mathgroup at smc.vnet.net
• Subject: [mg87005] Re: [mg86947] Re: Limit[(x - Log[Cosh ]) SinIntegral , x -> Infinity]
• From: Daniel Lichtblau <danl at wolfram.com>
• Date: Fri, 28 Mar 2008 03:19:00 -0500 (EST)
• References: <20080326082007.401$ci@newsreader.com> <200803271316.IAA19623@smc.vnet.net>

Szabolcs Horvát wrote:
> 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.
> [...]

I beg to differ. If that nonevaluation result is time consuming to 
compute, and is something that might show up in a context where 
recomputation is an issue, then caching can save considerable time.

Limits tend to be recomputed when one does, say, a definite integral 
requiring several different tactics. Caching them thus can reduce 
timings of Integrate, a notoriously slow function.

Daniel Lichtblau
Wolfram Research

• References:
  • Re: Limit[(x - Log[Cosh[x]]) SinIntegral[x], x -> Infinity]
    • From: "Szabolcs HorvÃt" <szhorvat@gmail.com>