(begin(load "util.scm");ex 1.16 计算b的幂
    (define (_expt product b n maxn)(if (= n maxn) product(if (<= (* n n) maxn) (_expt (* product product) b (+ n n) maxn)(_expt (* product b) b (+ n 1) maxn))))(define (fast-expt b n)(if (<= n 0) 1(_expt b b 1 n)));ex 1.11
    (define (ex1-f n)(cond ((< n 3) n)(else(+ (ex1-f (- n 1)) (* 2 (ex1-f (- n 2))) (* 3 (ex1-f (- n 3)))))))            (define (expmod base exp m)(cond ((= exp 0) 1)((even? exp)(remainder (square (expmod base (/ exp 2) m))m))(else(remainder (* base (expmod base (- exp 1) m))m))))
;    (define (expmod base exp m)
;        (remainder (fast-expt base exp) m))
    (define (fermat-test n)(define (try-it a)(= (expmod a n n) a))(try-it (+ 1 (random (- n 1)))))(define (fast-prime? n times)(cond ((= times 0) true)((fermat-test n) (fast-prime? n (- times 1)))(else false)))
;    (define (sum term a next b)
;      (if (> a b)
;          0
;          (+ (term a)
;             (sum term (next a) next b))));ex 1.30
    (define (sum term a next b)(define (iter a result)(if (> a b)result(iter (next a) (+ (term a) result))))(iter a 0));ex 1.31
    (define (product term a next b)(define (iter a result)(if (> a b)result(iter (next a) (* (term a) result))))(iter a 1));ex 1.32
    (define (accumulate1 combiner null-value term a next b)(define (iter a result)(if (> a b)result(iter (next a) (combiner (term a) result))))(iter a null-value));ex 1.33
    (define (filtered-accumulate filter combiner null-value term a next b)(define (iter a result)(if (> a b)result(if (filter a)(iter (next a) (combiner (term a) result))(iter (next a) result))))(iter a null-value))        (define (inc n) (+ n 1))(define (cube x) (* x x x))(define (sum-cubes a b)(sum cube a inc b))(define (identity x) x)(define (sum-integers a b)(accumulate1 + 0 identity a inc b))(define (product-integers a b)(accumulate1 * 1 identity a inc b))(define (sum-integers-even a b)(filtered-accumulate even? + 0 identity a inc b))(define (product-integers-even a b)(filtered-accumulate even? * 1 identity a inc b))
;    (define (sum-integers a b)
;      (sum identity a inc b))
;    (define (product-integers a b)
;      (product identity a inc b))
)