topic Re: Problem with the addition of two values (positive and negative) - SAS Data Integration Studio in SAS Data Management

Problem with the addition of two values (positive and negative) - SAS Data Integration Studio

vfarmak — Tue, 28 Jan 2020 13:41:38 GMT

Dear all,

I have a table with two columns as listed below:

Col_1	Col_2
0.2	-0.2

I then use an extract field and I create a calculated field "Col_3", which has the following expression

Col_1 + Col_2

The result of the addition should be equal to zero (0).

Instead, the following value is produced: 2.6841454E21

I have already tried to round the value, but nothing is happening.

Furthermore, when I use format and informat (which is something that I do not want, but after trying to troubleshoot the problem), a negative zero value is displayed.

Does anyone have any clue about this?

Thanks in advance,

Vasileios

Re: Problem with the addition of two values (positive and negative) - SAS Data Integration Studio

PaigeMiller — Tue, 28 Jan 2020 13:48:19 GMT

This is roundoff error, and there's really no way to avoid this using computers. The problem is the 0.2 cannot be represented exactly as a string of 0s and 1s (which is how computers represent numbers).

If you really want a zero there, you can use the FUZZ() function.

if fuzz(col_1+col_2)=0 then col_3=0;
else col_3=col_1+col_2;

Re: Problem with the addition of two values (positive and negative) - SAS Data Integration Studio

novinosrin — Tue, 28 Jan 2020 13:58:42 GMT

I was watching a documentary the other day that was about the same reason for Warren Buffet not to trust computers in general 🙂

Re: Problem with the addition of two values (positive and negative) - SAS Data Integration Studio

PaigeMiller — Tue, 28 Jan 2020 14:01:08 GMT

@novinosrin wrote:

I was watching a documentary the other day that was about the same reason for Warren Buffet not to trust computers in general 🙂

According to Mr. Buffet, is there a method that does not contain the possibility of error, and would be preferable?

Re: Problem with the addition of two values (positive and negative) - SAS Data Integration Studio

ballardw — Tue, 28 Jan 2020 15:39:08 GMT

@PaigeMiller wrote:

@novinosrin wrote:

I was watching a documentary the other day that was about the same reason for Warren Buffet not to trust computers in general 🙂

According to Mr. Buffet, is there a method that does not contain the possibility of error, and would be preferable?

I would add:

And can be done in an acceptable amount of time.

Pencil and paper with a properly trained person can do anything a computer can. It just takes time.