Multiplying floating point numbers

[SuryaKiran]

Hi SAS Users,

Today I came across very weird issue in SAS. I just multplied two floating point values and the result is not accurate to actual values.

If we calculate 0.014x88683.537=1241.569, but SAS give different answer.

DATA test2;
set test;
Mul=num1*num2;
RUN;

[WarrenKuhfeld]

Use a format like best16. instead of 5.3 and 12.3 and you will get values closer to the true values.  Multiple them and see if you get something closer to the expected results.

[SuryaKiran]

Still the same results after using best16.

[WarrenKuhfeld]

The SAS product will be the same.  The point is if you multiply the numbers together using a calculator, your results will come closer than they did before.

[SuryaKiran · Accepted solution]

Figured out the issue: num1 is shown as rounded to 3 decimal values, but when performing the calculation it is not rounded to 3 decimals. 

[WarrenKuhfeld]

Right.  That is why I wanted you to display the numbers with more precision before multiplying them together to compare to the product that SAS reports.

[ChrisNZ]

SAS gives the correct answer for your example.

data t;
  x=0.014*88683.537;

  putlog x= 32.16;
run;

x=1241.5695180000000000

Go to https://www.wolframalpha.com/input/?i=0.014x88683.537

for a calculation with many more digits than SAS or your calculator will display.