sicp

sicp 2.20

Exercise 2.20.  The procedures +, *, and list take arbitrary numbers of arguments. One way to define such procedures is to use define with dotted-tail n
Bloodwolf·2011-07-24 00:00

sicp 2.19

Exercise 2.19.  Consider the change-counting program of section 1.2.2. It would be nice to be able to easily change the currency used by the program, so that we could compute th
Bloodwolf·2011-07-24 00:00

sicp 2.18

  Exercise 2.18.  Define a procedure reverse that takes a list as argument and returns a list of the same elements in reverse order:     (reverse (list 
Bloodwolf·2011-07-21 23:00

sicp 2.17

Exercise 2.17.  Define a procedure last-pair that returns the list that contains only the last element of a given (nonempty) list:     (last-pair (list 23
Bloodwolf·2011-07-21 23:00

sicp 2.16

Exercise 2.16.  Explain, in general, why equivalent algebraic expressions may lead to different answers. Can you devise an interval-arithmetic package that does not have this shortcoming,
Bloodwolf·2011-07-21 23:00

sicp 2.15

Exercise 2.15.  Eva Lu Ator, another user, has also noticed the different intervals computed by different but algebraically equivalent expressions. She says that a formula to compute with in
Bloodwolf·2011-07-21 23:00

sicp 2.14

Exercise 2.14.  Demonstrate that Lem is right. Investigate the behavior of the system on a variety of arithmetic expressions. Make some intervals Aand B, and use them in computing
Bloodwolf·2011-07-21 23:00

名言

nothingbrings peoplecloserthanacommonenemy.Nothingyieldsmeatyproblemslikestarting withthewrongassumptions.SICP
zzljlu·2011-07-21 19:00

sicp 2.13

Exercise 2.13.  Show that under the assumption of small percentage tolerances there is a simple formula for the approximate percentage tolerance of the product of two intervals in terms of t
Bloodwolf·2011-07-20 10:00

sicp 2.12

Exercise 2.12.  Define a constructor make-center-percent that takes a center and a percentage tolerance and produces the desired interval. You must also define a selector perc
Bloodwolf·2011-07-19 19:00

sicp 2.11

Exercise 2.11.  In passing, Ben also cryptically comments: ``By testing the signs of the endpoints of the intervals, it is possible to break mul-interval into nine cases, only one
Bloodwolf·2011-07-19 19:00

sicp 2.10

Exercise 2.10.  Ben Bitdiddle, an expert systems programmer, looks over Alyssa's shoulder and comments that it is not clear what it means to divide by an interval that spans zero. Modify Aly
Bloodwolf·2011-07-19 18:00

sicp 2.9

Exercise 2.9.  The width of an interval is half of the difference between its upper and lower bounds. The width is a measure of the uncertainty of the number specified by the inter
Bloodwolf·2011-07-19 18:00

sicp 2.8

Exercise 2.8.  Using reasoning analogous to Alyssa's, describe how the difference of two intervals may be computed. Define a corresponding subtraction procedure, called sub-interval. &
Bloodwolf·2011-07-19 13:00

sicp 2.7

Exercise 2.7.  Alyssa's program is incomplete because she has not specified the implementation of the interval abstraction. Here is a definition of the interval constructor:   &nbs
Bloodwolf·2011-07-19 13:00

sicp 2.6

 Exercise2.6.  Incaserepresentingpairsasprocedureswasn'tmind-bogglingenough,considerthat,inalanguagethatcanmanipulateprocedures,wecangetbywithoutnumbers(atleastinsofarasnonnegativeintegersareconcerned
Bloodwolf·2011-07-19 13:00

SICP Exercise 3.55

Exercise3.55从上图中可以看到，partial-sums的第i个元素等于其第(i-1)个元素加上stream的第i个元素。所以代码如下：(define(partial-sumss) (cons-stream(stream-cars) (add-streams(partial-sumss) (stream-cdrs))))但是，上面的代码在s是有限的流之后，就会报错，这是由于（partia
zzljlu·2011-07-17 14:00

SICP Exercise 3.54

Exercise3.54;;Exercise3.54 (define(mul-streamss1s2) (stream-map*s1s2)) (definefactorials(cons-stream1(mul-streams(integers-starting-from2) factorials)))由于n!=(n-1)!*n，所以就有了上述的代码。
zzljlu·2011-07-17 12:00

SICP Exercise 3.53

方法二：（http://wqzhang.wordpress.com/2009/08/08/sicp-exercise-3-53/）设s=(1x2x3x4...)
zzljlu·2011-07-17 12:00

SICP Exercise 3.52

seq的内容正常应该是(13610152128364555667891105120136153171190210)，其中第i个值是由1到i的和而得到的。>(definesum0) >sum 0 >(define(accumx) (set!sum(+xsum)) sum) >sum 0 >(defineseq(stream-mapaccum(stream-enumerate-interval120)
zzljlu·2011-07-15 16:00

SICP Exercise 3.51

SICPExercise3.51>(definex(stream-mapshow(stream-enumerate-interval010))) 0 >(stream-refx5) 1 2 3 4 5
zzljlu·2011-07-15 16:00

10 Tips for Proper Application Logging

tips-proper-application-logging.htmlOurlatestJCPpartner,TomaszNurkiewicz,hassubmittedanumberofpostsdescribingthebasicprinciplesofproperapplicationlogging.Ifound
LibNux·2011-07-15 15:00

SICP Exercise 3.50

SICPExercise3.50(define(stream-mapproc.argstreams) (if(stream-null?
zzljlu·2011-07-15 15:00

sicp 2.5

Exercise 2.5.  Show that we can represent pairs of nonnegative integers using only numbers and arithmetic operations if we represent the pair a and b as the integer that
Bloodwolf·2011-07-14 16:00

sicp 2.4

Exercise 2.4.  Here is an alternative procedural representation of pairs. For this representation, verify that (car (cons x y))yields x for any objects x and 
Bloodwolf·2011-07-14 16:00

SICP Exercise 3.38

SICPExercise3.38a)Ilistalltheordersofthethreeprocess,andthendeterminethevalueofbalance.Forsimplicity,
zzljlu·2011-07-13 14:00

SICP Exercise 3.37

SICPExercise3.37;;;Exercise3.37 (define(c+xy) (let((z(make-connector))) (adderxyz) z)) (define(c-xy)
zzljlu·2011-07-13 10:00

SICP Exercise 3.35

SICPExercise3.35;;;Exercise3.35 (define(squarerab) (define(process-new-value) (if(has-value?
zzljlu·2011-07-13 09:00

SICP Exercise 3.34

SICPExercise3.34(define(squarerab) (multiplieraab))Theflawisthat:supposeweset thevalueofb to9,butthesquarercannotdeterminethevalueofa
zzljlu·2011-07-13 09:00

SICP Exercise 3.33

SICPExercise3.33Thisissimilarasthecelsius-fahrenheit-converterprocedure.
zzljlu·2011-07-13 09:00

sicp 2.3

Exercise 2.3.  Implement a representation for rectangles in a plane. (Hint: You may want to make use of exercise 2.2.) In terms of your constructors and selectors, create procedures tha
Bloodwolf·2011-07-12 22:00

sicp 2.2

  Exercise 2.2.  Consider the problem of representing line segments in a plane. Each segment is represented as a pair of points: a starting point and an ending point. Define a construc
Bloodwolf·2011-07-12 21:00

sicp 2.1

Exercise 2.1.  Define a better version of make-rat that handles both positive and negative arguments. Make-rat should normalize the sign so that if the rational number is positive, both the
Bloodwolf·2011-07-12 21:00

sicp 1.46

Exercise 1.46.  Several of the numerical methods described in this chapter are instances of an extremely general computational strategy known as iterative improvement. Iterative improvement
Bloodwolf·2011-07-12 00:00

sicp 1.45

 Exercise1.45.  Wesawinsection 1.3.3thatattemptingtocomputesquarerootsbynaivelyfindingafixedpointofyx/ydoesnotconverge,andthatthiscanbefixedbyaveragedamping.Thesamemethodworksforfindingcuberootsasfixe
Bloodwolf·2011-07-12 00:00

sicp 1.44

Exercise 1.44.  The idea of smoothing a function is an important concept in signal processing. If f is a function and dx is some small number, then the smoothed version of f is the function
Bloodwolf·2011-07-11 01:00

sicp 1.43

 Exercise1.43.  Iffisanumericalfunctionandnisapositiveinteger,thenwecanformthenthrepeatedapplicationoff,whichisdefinedtobethefunctionwhosevalueatxisf(f(...(f(x))...)).Forexample,iffisthefunctionxx+1,t
Bloodwolf·2011-07-11 00:00

sicp 1.42

Exercise1.42.  Letfandgbetwoone-argumentfunctions.Thecompositionfaftergisdefinedtobethefunctionxf(g(x)).Defineaprocedurecomposethatimplementscomposition.Forexample,ifincisaprocedurethatadds1toitsargum
Bloodwolf·2011-07-11 00:00

sicp 1.41

Exercise 1.41.  Define a procedure double that takes a procedure of one argument as argument and returns a procedure that applies the original procedure twice. For example, if inc is a proce
Bloodwolf·2011-07-10 23:00

sicp 1.40

  Exercise 1.40.  Define a procedure cubic that can be used together with the newtons-method procedure in expressions of the form     (newtons-method (cubic a&n
Bloodwolf·2011-07-10 23:00

sicp 流 函数(3-53 to 3-58,3-59,3-60,3-61,3-62 答案)

;;;--------3.53------------------------------(define(add-streams1s2) (stream-map+s1s2))defines(cons-stream1(add-streamss)))定义2^n流函数(n为从0开始的整数，为流的第n个元素);;;---------3.54-----------------------------(def
joans123·2011-07-10 18:00

sicp stream-map 函数(3-50,3-51,3-52答案)

;;;stream-map扫描流执行proc，允许带多个流(每个流的元素个数应该相等)(define(stream-mapproc.argstreams) (if(stream-null?(carargstreams))     the-empty-stream     (cons-stream      (applyproc(mapstream-carargstreams))      (app
joans123·2011-07-09 23:00

linux WIFI P2P

overviewForanintroductionseetheslidesforthe"Wi-FiPeer-to-PeeronLinux"talkgivenbyJohannesBergduringtheLinuxPlumbersConference2010.BasicP2PArchitectureStack
magod·2011-07-09 13:00

SICP Exercise 3.29

SICPExercise3.29weknowthat AorB isequivalentto not((notA)and(notB))from UsingDe-Morgan’srules.thediagramis
zzljlu·2011-07-08 14:00

SICP Exercise 3.28

SICPExercise3.28Thisexerciseiseasy.
zzljlu·2011-07-08 14:00

SICP Exercise 3.25

SICPExercise3.25Thisexerciseisalittlemoredifficult.Iusealistasthekey,thefollowingdiagramwillhelpyoutowritecorrectcode.whenyouwritecode
zzljlu·2011-07-07 22:00

转： Android PreferenceActivity简介

PerferenceActivity是什么，看下面的截图：Android系统截图      MusicPlayerSetting截图  好了，我们看到Android系统本身就大量用到了PreferenceActivity
zhujianjia·2011-07-07 16:00

SICP Exercise 3.22

HereistheimplementationofQUEUEasaprocedurewithlocalstate.;;;QUEUEasaprocedurewithlocalstate (define(make-queue) (let((front-ptrnil) (rear-ptrnil)) (define(dispatchm) (cond((eq?m'empty-queue?)empty-que
zzljlu·2011-07-07 11:00

SICP Exercise 3.11

1，Theresultof (defineacc(make-account50)):2,Environmentswhenevaluating((acc'deposit)40):3,Resultof((acc'deposit)40):4, Environmentswhenevaluating((acc'withdraw)60):5,Theresultof((defineacc2(make-accou
zzljlu·2011-07-06 16:00

获取手机左边音量＋ －按键的事件方法或私有api

MPMusicPlayerController *ipodMusicPlayer = [MPMusicPlayerController iPodMusicPlayer];   
linwwwei·2011-07-04 19:00
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