ELisp: Arithmetic
;; addition (+ 4 5 1) ; 10
;; Subtraction (- 9 2) ; 7 (- 9 2 3) ; 4
;; Multiplication (* 2 3) ; 6 (* 2 3 2) ; 12
;; Division ;; WARNING: 7 divided by 2 returns 3, not 3.5, ;; because the division function return a int when both operands are int. ;; integer part of quotient (/ 7 2) ; 3 ;; WARNING: 2. is still a int. 2.0 is a float. (/ 7 2.) ; 3 ;; int divide by float return float (/ 7 2.0) ; 3.5
;; test if a number is integer or float (integerp 2) ; t (integerp 2.) ; t (integerp 2.0) ; nil (floatp 2) ; nil (floatp 2.) ; nil (floatp 2.0) ; t
Note: Function names that end with a “p” often means it return either true or false. (The “p” stands for “predicate”) t means true; nil means false.
;; modular arithmetic, remainder (% 7 4) ; 3
;; Power; Exponential (expt 2 3) ; 8