Difference b/n Real Numbers in logix 5000

Hi chaps!!

Considering the following example of doing subtraction of 2 real number in rs logix 5000(L75),Why we are getting the result as .100000038 and why not exactly 0.1.

Example:
SourceA = 10.1
SourceB = 10.0
Destination=0.100000038
Above tags are of real types!

Cheers!

'Real' data types are always approximations. It's similar to .33333 being an approximation of the fraction 1/3. There is no way using a finite number of decimal digits to precisely represent 1/3. They are most accurate in storing x/10, x/100 etc.

The 'Real' data types are most accurate at storing x/2, x/4, x/8 etc.

Try this floating point calculator.

Note that '10.1' is stored in its best accuracy as 10.100000381469727

'10.0' because it doesn't have a fraction is stored accurately.

Thus the difference you receive.

Google 'Floating Point' or 'IEEE 754' and start reading.

Thanks a lot Bernie,especially for the calculator which resolved my query on floating point.

Great tool Bernie - bookmarked...