Sicp Exercise 1.30

Exercise 1.30. The sum procedure above generates a linear recursion. The procedure can be rewritten so that the sum is performed iteratively. Show how to do this by filling in the missing expressions in the following definition:

(define (sum term a next b)
(define (iter a result)
(if

(iter )))
(iter ))

	(define (inc n) (+ n 1))
	(define (identity x) x)
	(define
	(sum-iter-helper
	runningsum
	termfunction
	termvalue
	nextfunction
	upperbound)
	(if
	(> termvalue upperbound)
	runningsum
	(sum-iter-helper
	(+ runningsum (termfunction termvalue))
	termfunction
	(nextfunction termvalue)
	nextfunction
	upperbound)))
	(define (sum term a next b)
	(sum-iter-helper
	0
	term
	a
	next
	b))
	(define (sum-integers a b)
	(sum identity a inc b))
	(sum-integers 1 10)

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