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Re: why no result & no error from this recursion

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82436] Re: [mg82403] why no result & no error from this recursion
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Sat, 20 Oct 2007 05:51:46 -0400 (EDT)
  • Organization: Mathematics & Statistics, Univ. of Mass./Amherst
  • References: <200710190904.FAA05304@smc.vnet.net> <DB2B10DE-2D39-482A-ACA4-6DDB5CECB1E4@jeol.com>
  • Reply-to: murray at math.umass.edu

When the evaluation ended (very quickly, and with no result), the front 
end was immediately ready for the next input I typed.

Sseziwa Mukasa wrote:
> 
> On Oct 19, 2007, at 5:04 AM, Murray Eisenberg wrote:
> 
>> Why does the following recursion produce neither a result nor an error
>> message -- nor a system crash?
>>
>> Block[{$RecursionLimit=50002}, (If[#<1, "", "." <> #0[# - 1]] &)[50000]]
>>
>> I even tried setting $RecursionLimit=Infinity, but no change.
>>
>> I presume this is just bumping up against a hardware/OS limit, so I'm
>> surprised to get no error message and no crash.
> 
> My guess is that the front end is having problems formatting 50000 '.' 
> for display.  I've noticed sometimes that calculations that generate 
> long strings on output can appear to have hung but the kernel has not 
> crashed and the front end is unresponsive.
> 
> Regards,
> 
> Ssezi
> 

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305


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