topic Re: question related to LE operator in SAS Programming

question related to LE operator

Sheeba — Tue, 27 Dec 2016 19:28:44 GMT

Hi,

I am trying to run the below code.

data one;

input a b;

datalines;

12.45 12.40

13.55 13.50

17.50 17.45

14.70 14.76

15.47 15.50

;

run;

data two;

set one;

diff1= abs(b-a);

if abs(b-a) le 0.05 then result='success';

else result='failure';

run;

The second and third row has diff1 equal to 0.05 but the result is getting value failure. First row is getting values appropriately.

Appreciate any help.

Regards,

Sheeba

Re: question related to LE operator

Reeza — Tue, 27 Dec 2016 20:56:34 GMT

Round the numbers before you do a calculation.

Numbers cannot be stored exactly so the number is likely 0.050000001 or something like that.

http://support.sas.com/documentation/cdl/en/lrcon/69852/HTML/default/viewer.htm#p0ji1unv6thm0dn1gp4t01a1u0g6.htm

Re: question related to LE operator

Patrick — Tue, 27 Dec 2016 21:23:23 GMT

As @Reeza wrote: It's about rounding and how computers store values.

Run below code and have a look at the "data two"

data one;
  input a b;
  datalines;
12.45 12.40
13.55 13.50
17.50 17.45
14.70 14.76
15.47 15.50
;
run;

data two;
  set one;
  format diff1 diff2 best32.;
  diff1= abs(b-a);
  diff2=round(diff1,0.000001);
  if round(abs(b-a),0.0000001) le 0.05 then
    result='success';
  else result='failure';
run;

It's not so that SAS does something wrong but it is a common trap and I'd wish for some system option which would allow us to define a max. precision so that rounding happens implicitely.

Re: question related to LE operator

Loko — Wed, 28 Dec 2016 08:56:37 GMT

Hello,

I totally agree with @Patrick ' s proposal about the rounding . I have met many people working with SAS failing to deal properly with number calculation.

If I may , I would add a note in the log specifying the implicit rounding (when it takes place).

@Patrick could you open a topic so the community votes for this proposal ?

Re: question related to LE operator

Sheeba — Wed, 28 Dec 2016 17:57:48 GMT

Hi Reeza,

Thanks a lot for the details.

It is working as expected now

Regards,

Sheeba

Re: question related to LE operator

Sheeba — Wed, 28 Dec 2016 18:00:27 GMT

Hi Patrick,

Thanks for helping me out. With rounding the issue is resolved.

The option to define a max precision will be nice to have in such cases .

Thanks again,

Regards,

Sheeba

Re: question related to LE operator

Sheeba — Wed, 28 Dec 2016 18:02:02 GMT

Hi Loko,

Thanks for the reply. Yes rounding resolved the issue here

Regards,

Sheeba