Comparing floating point values

Question

I just read a statement about the floating point value comparison

Floating point values shall not be compared using either the == or != operators.

Answer 1

Generally floating point numbers should be compared using a construct like

if( abs((x1 - x2) < 0.001) )

The reason for the warning you quoted is you may have two methods of calculating something, and they may be equal if you had no rounding error, but the rounding error makes them slightly different.