# [seqfan] Re: Using "Quiet" in Mathematica

Alonso Del Arte alonso.delarte at gmail.com
Sat Feb 18 20:03:27 CET 2012

```My two cents: Whenever practical, the program should avoid error messages.
If it's something as simple as starting at 1 or 2 rather than 0, then
that's what should be done.

But when it involves bloating the program so that it becomes very long,
then I think it's acceptable to wrap the program in Quiet. To me, "very
long" for a Mathematica program in the OEIS is more than four lines (so
your example of A031975 I don't find "very long" and it generates no
Part::partw error messages, or any error messages of any kind).

What should absolutely be avoided is turning off error messages for the
rest of the user's session, because the user might not realize that this
has happened.

This is more or less what I wrote in
https://oeis.org/w/index.php?title=Style_sheet_for_Mathematica_programs&stable=0

Al

On Sat, Feb 18, 2012 at 1:26 PM, Harvey P. Dale <hpd1 at nyu.edu> wrote:

>        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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--
Alonso del Arte
Author at SmashWords.com<https://www.smashwords.com/profile/view/AlonsoDelarte>
Musician at ReverbNation.com <http://www.reverbnation.com/alonsodelarte>

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