ODD _ _ _ _ _ _ _ _ _ _ _ _ declaration
This declaration is used to declare an operator odd in its first argument. Expressions involving an operator declared in this manner are transformed if the first argument contains a minus sign. Any other arguments are not affected.
odd f; f(-a) -F(A) f(-a,-b) -F(A,-B) f(a,-b) F(A,-B)
If say f is declared odd, then f(0) is replaced by zero unless f is also declared non zero by the declaration nonzero.