练习3-56 原文 Exercise 3.56. A famous problem, first raised by R. Hamming, is to enumerate, in ascending order with no repetitions, all positive integers with no prime factors ...

练习3-55 原文 Exercise 3.55. Define a procedure partial-sums that takes as argument a stream S and returns the stream whose elements are S0, S0 + S1, S0 + S1 + S2, …. For examp...

练习3-64 原文 Exercise 3.64. Write a procedure stream-limit that takes as arguments a stream and a number (the tolerance). It should examine the stream until it finds two succe...

练习3-81 原文 Exercise 3.81. Exercise 3.6 discussed generalizing the random-number generator to allow one to reset the random-number sequence so as to produce repeatable sequen...

练习3-63 原文 Exercise 3.63. Louis Reasoner asks why the sqrt-stream procedure was not written in the following more straightforward way, without the local variable guesses: (d...

练习3-82 原文 Exercise 3.82. Redo exercise 3.5 on Monte Carlo integration in terms of streams. The stream version of estimate-integral will not have an argument telling how man...

练习3-67 原文 Exercise 3.67. Modify the pairs procedure so that (pairs integers integers) will produce the stream of all pairs of integers (i,j) (without the condition i < j). ...

练习3-54 原文 Exercise 3.54. Define a procedure mul-streams, analogous to add-streams, that produces the elementwise product of its two input streams. Use this together with th...

练习3-52 原文 Exercise 3.52. Consider the sequence of expressions (define sum 0) (define (accum x) (set! sum (+ x sum)) sum) (define seq (stream-map accum (stream-enumerate...

练习3-66 原文 Exercise 3.66. Examine the stream (pairs integers integers). Can you make any general comments about the order in which the pairs are placed into the stream? For ...

练习3-53 原文 Exercise 3.53. Without running the program, describe the elements of the stream defined by (define s (cons-stream 1 (add-streams s s))) 分析 s是一串2的幂。也就是1...

练习3-72 原文 Exercise 3.72. In a similar way to exercise 3.71 generate a stream of all numbers that can be written as the sum of two squares in three different ways (showing h...

练习3-50 原文 Exercise 3.50. Complete the following definition, which generalizes stream-map to allow procedures that take multiple arguments, analogous to map in section 2.2.3...

练习3-58 原文 Exercise 3.58. Give an interpretation of the stream computed by the following procedure: (define (expand num den radix) (cons-stream (quotient (* num radix) den) ...

练习3-77 原文 Exercise 3.77. The integral procedure used above was analogous to the “implicit” definition of the infinite stream of integers in section 3.5.2. Alternatively, w...

练习3-68 原文 Exercise 3.68. Louis Reasoner thinks that building a stream of pairs from three parts is unnecessarily complicated. Instead of separating the pair (S0,T0) from th...