From the manual:
Quote:
!! #define lines normally don't end with a semicolon, unless you want value to end with a semicolon for some reason. Some PRAGMA defines (see below) require a semicolon for ending a text string.


this means that '#define PI 3.14;' includes the semicolon within the equation in which you use PI, so the compiler reads the semicolon in the middle of the equation, where it 'cuts' the equation into two pieces - which are getting almost always senseless this way.