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question related to LE operator

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Regular Contributor
Posts: 162

question related to LE operator

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

Super User
Posts: 17,750

Re: question related to LE operator

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#p0ji1unv6thm0dn1gp4t...

Regular Contributor
Posts: 162

Re: question related to LE operator

Hi Reeza,

 

Thanks a lot for the details.

 

It is working as expected now

Regards,

Sheeba

Respected Advisor
Posts: 3,887

Re: question related to LE operator

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.

Super Contributor
Posts: 305

Re: question related to LE operator

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 ?

Regular Contributor
Posts: 162

Re: question related to LE operator

Hi Loko,

 

Thanks for the reply. Yes rounding resolved the issue here

 

Regards,

Sheeba

Regular Contributor
Posts: 162

Re: question related to LE operator

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

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