issue with proc format

[deleted_user]

Hi
I am trying to run below sas code and its giving me unexpected result.Can I have help on this.


In both case1 and case2 val3 is assigned -600 but the value of val4 derived from the format is differing.


proc format;
Value u33mbchg

low - -600 = ' 94.7649 '

-600 <- -200 = ' 95.8705 '

-200 <- -100 = ' 99.4335 '

-100 <- high = ' 100.9247 ' ;

run;



case1:

Data T1;

val1=sum(440.0001,0.01);

val2=sum(1040.0001,0.01);

val3=Sum(0,val1)-Sum(0,val2);

val4 = 1*put(val3,u33mbchg.);

run;

output
val1=440.0101
val2=1040.0101
val3=-600
val4=94.7649




Using the above proc format we ran the same code with different input value in val1 and val2 as below:

case2:
Data T1;

val1=sum(440.1,0.01);

val2=sum(1040.1,0.01);

val3=Sum(0,val1)-Sum(0,val2);

val4 = 1*put(val3,u33mbchg.);

run;

output:
val1=440.11
val2=1040.11
val3=-600
val4=95.8705

[Diane_SAS]

What value do you expect to be the correct one for val4?

[hdo]

Due to the ( lack of ) precision in floating point operations on the computer , the value val3 is nor excactly -600 in both cases.

insert
valx=val3+600;
put valx= 20.15;

in each data step and you will see

valx=0.000000000000000
and
valx=0.000000000000114
and since the format is separated on either side of -600 , the results differ.
At least on mi Intel based computer.