Fibonacci numbers (bc)

/*
   Compute (huge) Fibonacci numbers using bc,
   Henning Polzer, 19. April 2015
*/

define fibonacci (z) {

   if (z < 1) return 0 else
     if (z < 3) return 1

   m = n = 1

   for (i = 2; i < z; i++) {
     summe = m + n
     m = n
     n = summe
   }

   return summe
}