an invalid type argument for unary * exception
The star is used for two purposes in C:

- a multliplication of two numbers (a binary *)
- a reference to the content pointed by an address (a unary *)

Here, it seems the compiler is considering that the star is used for the second purpose, for some reasons I dont know until I can see the code (my guess is that there is a ";" at the end of #define PI ..., and this is not important if PI is used at the end of the formula, but it matters if PI is used before the end).