Can't compile FSin trig function

[patters]

I'm new to the compiler, using it on Mac OS. Compiling a simple test program works fine. If I paste in the code from the FSin function from the documentation it won't compile:

Code:

../sine.bas:16: error: Syntax Error. Unexpected token 'ELSE' <ELSE>
../sine.bas:17: error: Syntax Error. Unexpected token 'IF' <IF>
../sine.bas:44: error: Syntax Error. Unexpected token 'FUNCTION' <FUNCTION>

I can't understand why the compiler doesn't like this, it looks ok to me. However, I can see an IF without an END IF. This is not how this listing is expressed in the forum post where it was first published. However, adding the missing END IF doesn't appear to help with the compiler errors. What is the problem here?