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$RecursionLimit

• To: mathgroup at smc.vnet.net
• Subject: [mg37384] $RecursionLimit
• From: "Nick Fortescue" <nick.fortescue at smartspread.com>
• Date: Sat, 26 Oct 2002 02:03:06 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

Hi,

While testing something yesterday I discovered some behaviour which I
hoped
would be handled better by Mathematica's $RecursionLimit. Is this a
defectshow b
which should be reported to WRI?

It's a very simple example, in a notebook just type:
foo[x_] = foo[foo[x]]

You get the following error messages coming up one by one, with 4 beeps
(used copy as->Plain text). All of these messages seem sensible.
However,
Mathematica then eats all the CPU, and if you don't abort memory usage
goes
up and up until eventually I get a low virtual memory message from
Windows.
I guess this is something to do with pattern matching in error results.

In[1]:=
foo[x_] = foo[foo[x]]
$RecursionLimit::"reclim": "Recursion depth of \!\(256\) exceeded."
$RecursionLimit::"reclim": "Recursion depth of \!\(256\) exceeded."
$RecursionLimit::"reclim": "Recursion depth of \!\(256\) exceeded."
General::"stop": "Further output of \!\($RecursionLimit :: \"reclim\"\)
will
\
be suppressed during this calculation."
$IterationLimit::"itlim": "Iteration limit of \!\(4096\) exceeded."
$IterationLimit::"itlim": "Iteration limit of \!\(4096\) exceeded."
$IterationLimit::"itlim": "Iteration limit of \!\(4096\) exceeded."
General::"stop": "Further output of \!\($IterationLimit :: \"itlim\"\)
will
\
be suppressed during this calculation."


Platform: Mathematica 4.2 on both Windows XP and Mac OS X

Nick Fortescue
Smartspread Ltd.