Date:         Mon, 18 Dec 2000 12:53:11 -0500
Reply-To:     Gerhard Hellriegel <ghellrieg@T-ONLINE.DE>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         Gerhard Hellriegel <ghellrieg@T-ONLINE.DE>
Subject:      Re: Division by missing (Zero).

On Mon, 18 Dec 2000 12:11:05 -0500, Howard Schreier

Little addon: if you really want the system to provide the error message
and produce the missing values, you should set the option ERRORS= to a high
value. After the number of errors SAS should ignore, normally an abend
happens!
I'd prefer to make it explicite, something like:

if div=. then do;
  res=.;
  put "missing value for DIV...";
end;
else do;
  res=x/div;
end;

In this way you can deal with all kind of errors and the program always
continues.




<Howard_Schreier@ITA.DOC.GOV> wrote:

>The normal behavior of SAS is precisely what is requested in the original
>posting.
>
>When a divisor is missing, SAS skips the calculation, records a missing
>value for the result, and places a summary note in the log. It does not
halt
>(at least not under usual system options settings).
>
>This is called propagation of missing values, and applies to expression
>evaluation in general (not just to division).
>
>Division by zero (which is not illustrated in the sample data) is
>different. It makes a bigger mess in the log, but it does not stop
execution
>either.
>
>On Fri, 15 Dec 2000 17:09:03 -0800, kmself@IX.NETCOM.COM wrote:
>
>>on Fri, Dec 15, 2000 at 12:34:49PM -0800, Anna Henson
>(anna_henson@YAHOO.COM) wrote:
>>> Shiferaw_G wrote in message
>>> <038930B7F7AFD411AD8000508BCDEDAE0D52C8@PSBMAIL5>...
>>> >I have a data set as follow:
>>> >
>>> >Data T1;
>>> >Input C  D   E;
>>> >
>>> >Av_CD= C/D;
>>> >Av_DE=D/E;
>>> >
>>> >When one of the variables is missing I get division by zero and the
>whole
>>> >process is stopped. I want the process to continue with calculating the
>>> >Average of those variables which values and skip or flag those with
>missing
>>> >values. Is it possible to do that with SAS?
>>> >
>>> >Cards;
>>> >
>>> >1     3     4
>>> >3      .      4
>>> >.       5     .
>>> >
>>> >;
>>> >
>>
>>> Hi This is what I got from SAS website for division by Zero
>>>
>>>
>>>
>>> Just replace x/y with x/(y+(y=0)) - x*(y=0)
>>>
>>> I tried it, and it worked great.
>>
>>
>>At least two problems:
>>
>>  1.  What is the intended result where no calculation is performed --
>>      is it zero, missing, some other assigned value, or a special flag?
>>      This logic doesn't provide for this.
>>
>>  2.  The logic doesn't allow for missing values.  I believe a test for
>>
>>          ( abs( y ) gt 0 )
>>
>>      would be an improvement.  SI's example site should correct this.
>>
>>Note also: I prefer the lt, gt, and eq operators for platform
>>portability and lack of confusion with the SAS assignment operator '='.
>>Token overloading is a Bad Thing [tm], particularly for very frequently
>>used tokens whose alternative uses may be easily confused.
>>
>>As they say in Humboldt County, "Don't overload your tokin', dude".
>>
>>--
>>Karsten M. Self <kmself@ix.netcom.com>    http://kmself.home.netcom.com/
>> Evangelist, Zelerate, Inc.                      http://www.zelerate.org
>>  What part of "Gestalt" don't you understand?      There is no K5 cabal
>>   http://gestalt-system.sourceforge.net/        http://www.kuro5hin.org
>>