" A comparision with a simple if-statement and the == operator does not succeed."
Yes, it does succeed: their values are different, and so EQ correctly returns FALSE.
This is very easy to demonstrate:
"How do I compare these two double-values?"
Using EQ compares the values for exact equivalence, which is not robust if you are working with binary floating point numbers. In that case the robust appraoch is to compare the absolute difference against a tolerance:
"What is the differnece between these two values, if they are both of the same datatype and the same size?"