The standard C preprocessor uses integers only in conditionals. You can scale your coefficients by a suitable Exp.10 and divide them again in the C expression (define a constant like #define MULT 1000). This will not complicate the C code because the compiler should reduce the divide-constant-by-constant before generating code. Peter -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics