Date: Mon, 31 Oct 2005 16:44:20 -0500
Reply-To: Chang Chung <chang_y_chung@HOTMAIL.COM>
Sender: "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From: Chang Chung <chang_y_chung@HOTMAIL.COM>
Subject: Re: Trying to avoid division by zero...
On Mon, 31 Oct 2005 12:59:33 -0800, oseithedude@GMAIL.COM wrote:
>Hello, I have around 40 or so numeric variables in a small program I am
>Basically, the variables are being created as follows:
>var1 = (a/(b*c));
>var2 = (f/(h*d));
>var3 = (dog/(cat*mouse));
>var4 = (k/(l*var1));
>and so on for about 40 variables. My problem is that, even though the
>final data seems to be coming out correctly, I am getting thousands of
>"Division by zero detected..." errors for the cases where the
>denominator in the above equations equal zero. It turns out that if the
>denominator for any of the equations is equal to 0, then the variable
>actually does not need to be created anyway. Is it posible to write
>simple code that prevents the above mathematical operations from being
>performed if the denominator equals zero or do I have to encase each of
>the 40 variables I am creating with an if... then statement for the
>case that the variables in the denominator are equal to zero?
>Appreciate any help in this matter, thanks!!!
I think you answered your own question in the part:
"It turns out that if the denomicator for any of the equations is equal to
0, then the variable ..."
This would actually partition the data into two: observations that are used
in the calculations, and observations which are not. I would distinguish
these two groups of observations first and do the calculations on the former
group only like:
/* do something similar like this one to create a flag var */
inSample = not ((b=0) or (c=0) or (h=0) or (cat=0) or (mouse=0) or (L=0));
if inSample then do;
/* do calculations */
end; else do;
/* results set to missing */
If you save the inSample flag, then it will be useful later.