> <\body> <\hide-preamble> >>> \<#57FA\>\<#7840\>SICP\<#FF1A\>\<#7B2C\>3\<#8BFE\>> <\wide-tabular> || \<#7F16\>\<#7A0B\>\<#7684\>\<#57FA\>\<#672C\>\<#539F\>\<#7406\> > |<\cell> Elements of Programming > >| \<#8868\>\<#8FBE\>\<#5F0F\> |<\cell> Expressions >| \<#547D\>\<#540D\>\<#4E0E\>\<#73AF\>\<#5883\> |<\cell> Naming and the Evironment >| \<#7EC4\>\<#5408\>\<#5F0F\>\<#7684\>\<#6C42\>\<#503C\> |<\cell> Evaluating Combinations >| \<#590D\>\<#5408\>\<#51FD\>\<#6570\> |<\cell> Compound Procedures >| \<#51FD\>\<#6570\>\<#5E94\>\<#7528\>\<#7684\>\<#4EE3\>\<#6362\>\<#6A21\>\<#578B\> |<\cell> The Subsitution Model for Procedure Application >| \<#6761\>\<#4EF6\>\<#8868\>\<#8FBE\>\<#5F0F\>\<#548C\>\<#8C13\>\<#8BCD\> |<\cell> Conditional Expressions and Predicates >| \; |<\cell> \; >| \<#7EBF\>\<#6027\>\<#9012\>\<#5F52\>\<#548C\>\<#8FED\>\<#4EE3\> |<\cell> Linear Recursion and Iteration >| \<#6811\>\<#5F62\>\<#9012\>\<#5F52\> |<\cell> Tree Recursion >>> |<\hidden> \<#4EF6\>\<#8868\>\<#8FBE\>\<#5F0F\>\<#548C\>\<#8C13\>\<#8BCD\>\V\<#77ED\>\<#8DEF\>\<#8FD0\>\<#7B97\>> <\itemize> \<#5E94\>\<#7528\>\<#5E8F\>\<#6C42\>\<#503C\>\<#FF08\>Scheme\<#4F7F\>\<#7528\>\<#7684\>\<#662F\>\<#5E94\>\<#7528\>\<#5E8F\>\<#6C42\>\<#503C\>\<#FF09\> \<#6B63\>\<#5219\>\<#5E8F\>\<#6C42\>\<#503C\> \<#4F8B\>\<#5206\>\<#6790\>\<#FF1A\>\<#5B9E\>\<#73B0\>\<#6C42\>\<#7EDD\>\<#5BF9\>\<#503C\>\<#7684\>\<#591A\>\<#79CD\>\<#65B9\>\<#5F0F\>> <\with|par-columns|2> <\equation*> =||||>|0,>>||>|>||>|0.>>>>>|\> <\session|scheme|default> <\unfolded-io|Scheme] > (define (abs1 x) \ \ (cond ((\ x 0) x) \ \ \ \ \ \ \ \ ((= x 0) 0) \ \ \ \ \ \ \ \ (else (- x)))) <|unfolded-io> abs1 <\unfolded-io|Scheme] > (define (abs2 x) \ \ (if (\ x 0) \ \ \ \ \ \ x \ \ \ \ \ \ (- x))) <|unfolded-io> abs2 <\unfolded-io|Scheme] > (define (abs3 x) \ \ (or (and (\ x) x) (- x))) <|unfolded-io> abs3 <\unfolded-io|Scheme] > (abs1 1) <|unfolded-io> 1 <\unfolded-io|Scheme] > (abs1 -1) <|unfolded-io> 1 <\input|Scheme] > \; <\folded> <\question> \<#4E3A\>\<#4EC0\>\<#4E48\>\<#548C\>\<#662F\>\<#5FC5\>\<#987B\>\<#7684\>\<#FF1F\> <|folded> <\exercise> \<#4F7F\>\<#7528\>\<#5B9E\>\<#73B0\>\<#548C\>\<#3002\> \<#53C2\>\<#8003\>\<#6587\>\<#6863\>\<#FF1A\> \; > <\initial> <\collection> <\references> <\collection> >