topic Re: Calculation Error in SAS Programming

Calculation Error

teja04 — Wed, 14 Nov 2018 22:42:02 GMT

Hi All, I have two numeric variables A & B, each variable length is 8. For example, two variables have same values. When I was subtracting
2985014.3137841 - 2885014.3137841
I am getting the value -4.65661E-10. Does anyone
have any ideaa why it is showing such value instead of '0'.

Re: Calculation Error

novinosrin — Wed, 14 Nov 2018 22:46:58 GMT

data diff;
a=2985014.3137841 ;
b=2985014.3137841;
dif=a-b;
run;

proc print noobs;run;

SAS Output

The SAS System

a	b	dif
2985014.31	2985014.31	0

Re: Calculation Error

PGStats — Wed, 14 Nov 2018 23:00:02 GMT

The two number are not equal, they are just displayed as equal. A -4E-10 difference is not visible when you display only 7 decimals. See @novinosrin's demonstration above.

Re: Calculation Error

teja04 — Wed, 14 Nov 2018 23:13:49 GMT

Thank you novinosrin and PGStats. I have tried this.. but the problem was other values have different decimals. Maximum decimals I am having is 8. I am not supposed to use ROUND function.

Re: Calculation Error

PGStats — Wed, 14 Nov 2018 23:38:40 GMT

Why do you expect the difference to be zero?

Re: Calculation Error

Reeza — Wed, 14 Nov 2018 23:50:42 GMT

https://documentation.sas.com/?docsetId=lrcon&docsetTarget=p0ji1unv6thm0dn1gp4t01a1u0g6.htm&docsetVersion=9.4&locale=en

Re: Calculation Error

teja04 — Wed, 14 Nov 2018 23:57:49 GMT

Okay.. I got your point. Can't we display the numeric value other than -4E-10 value.

Re: Calculation Error

Reeza — Thu, 15 Nov 2018 00:28:43 GMT

Sure, just format it and it will look like a zero.

format diff 8.2;

Re: Calculation Error

Kurt_Bremser — Thu, 15 Nov 2018 08:40:48 GMT

@teja04 wrote:
I am not supposed to use ROUND function.

Don't be an idiot. The tool for removing such artifacts of SAS numerical precision issues is the round() function, so use it. See Maxim 14.