The lisp-way to solve Fibonnaci

Question

I wanted to try and learn Lisp, but I very quickly gave up. I figured I\'d try again. I\'m looking at Problem 2 on Project Euler - finding the sum of all even Fibonacci numbers

Answer 1

;;; I try to write code as suggestion of @PESTO

(defun Fibo-Test (n / one_prior two_prior curr sum i)

(setq i 2) (setq one_prior 1 two_prior 1 )

(cond

((= n 0) (setq sum 0) )

((= n 1) (setq sum 1) )

((= n 2) (setq sum 1) )

(T

(while (and (< i n) (< sum (* 4 1e6)))

;;; convert to Real-num

(setq sum (+ (float one_prior) (float two_prior)))

(setq i (1+ i))

(setq curr sum) (setq
one_prior two_prior two_prior curr
)

) ; end while

) ; end cond(T)

) ; end cond

(princ (strcat "\nF(" (itoa i) ") = " (RTOS sum) " . "))

(princ)

) ; end function Fibo-Test