why '==' is not working properly, or what do I do wrong?

I just want to know why this happens...

[Bob Thompson]

More than likely this is a limitation of the binary. If you expand the number of sigfigs on a(5) and b(100) you will likely find that some small decimal place is slightly different.

Answer 1

[Jos (10584)]

There is a small difference, as shown by subtraction:

b(100)-a(5)

To tolerate such a small difference between x and y, try this

abs(x-y) < .0001