gistfile1.scm

(define (sum term a next b)  
  (if (> a b)  
   0  
    (+ (term a)  
       (sum term (next a) next b))))  
; (define (pi-sum a b)  
;   (define (pi-term x)  
;     (/ 1.0 (* x (+ x 2))))  
;   (define (pi-next x)  
;     (+ x 4))  
;     (sum pi-term a pi-next b))  

(define (pi-sum a b)  
  (sum (lambda (x) (/ 1.0 (* x (+ x 2))))  
       a  
       (lambda (x) (+ x 4))  
       b))  

(print (pi-sum 5 10))