[seqfan] Re: Using "Quiet" in Mathematica: Quiet or Quit?

Harvey P. Dale hpd1 at nyu.edu
Sun Feb 19 15:43:19 CET 2012

	Mathematica now has a command called Quiet that is different than Quit.  I'm using Mathematica 8.

-----Original Message-----
From: zak seidov [mailto:zakseidov at yahoo.com] 
Sent: Sunday, February 19, 2012 9:35 AM
To: Harvey P. Dale
Subject: Re: [seqfan] Using "Quiet" in Mathematica: Quiet or Quit?

Sorry, Harvey,
do yo mean Quit[]?
In my M5.2, I don't have Quiet.

---- Original Message -----
> From: Harvey P. Dale <hpd1 at nyu.edu>
> To: Sequence Fanatics Discussion list <seqfan at list.seqfan.eu>
> Cc: 
> Sent: Saturday, February 18, 2012 8:26 PM
> Subject: [seqfan] Using "Quiet" in Mathematica
>     I would like guidance, and perhaps a consensus or rule, about 
> whether and when to use "Quiet" in Mathematica programs in the OEIS.
>     Here's an example: A031795 lists numbers such that there are 
> exactly 27 occurrences of the digit 1 in the period of the continued 
> fraction of the square root of the number.  In Mathematica, it is easy 
> to generate the terms of the period of the continued fraction -- 
> ContinuedFraction[Sqrt[n]][[2]] does that.  It is also easy to count 
> the number of ones in that period, using Count.  The problem is that 
> every number that is a perfect square causes an error message to be 
> generated since there is no period of the continued fraction for the 
> square root of a perfect square.
>     There are two ways to deal with this.  One is simply to wrap the 
> Mathematica program inside "Quiet."  The second is to write a program 
> that avoids the error messages, in this case by separately testing for 
> perfect-square status.  I chose the latter for the program I submitted 
> for A031795.  But there are two problems with this choice:
> (1) it makes the program more opaque to the readers of the OEIS and 
> (2) it takes additional time to write such an error-code-avoiding program.
> (Indeed, in some instances I am not readily able to figure out how to 
> avoid the error messages and so cannot easily write a program that 
> avoids their generation.)
>     Using Quiet to eliminate the error messages, however, might be 
> dangerous because some of the messages generated might be material, 
> e.g., they might deal with precision errors or erroneous terms being 
> generated.
>     I would assume that no one would want to use Quiet when its effect 
> might be to pollute the accuracy of the OEIS.  The question really is: 
> if it appears clear that the error messages being generated are not of 
> the dangerous variety, should Quiet be permitted in lieu of having to 
> figure out and submit what will always be a more complex Mathematica 
> program?
>     I would appreciate guidance.
>     Best,
>     Harvey
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