变换规则与定义ppt课件

1、 TOPexpr /. rules在表达式上应用一次规则expr /. rules在表达式上重复应用规则直道结果不再改变expr /. lhs - rhs在表达式上应用某个变换规则expr /. lhs1 - rhs1, lhs2-rhs, .在表达式上依次应用一系列规则expr /. rules1, rules2, .应用一组规则得到一个数组 TOPexpr /. rulesapply rules to all subparts of exprReplace expr, rulesapply rules to the whole of expr onlyReplace expr, rules

2、, levspecapply rules to parts of expr on levels specified by levspecReplace expr, rulesapply rules in one way onlyReplaceList expr, rulesapply rules in all possible ways TOP TOP TOP TOP TOP TOP TOP TOP TOP TOP TOPAssociating definitions with different symbolsfargs := rhsdefine a downvalue for ffgarg

3、s, . := rhsdefine an upvalue for gShorter ways to define upvaluesfg = value or fgargs = valuemake assignments to be associated with g, rather than ffg:=value or fgargs := valuemake delayed assignments associated with gfarg1, arg2, . = valuemake assignments associated with the heads of all the argi T

4、OPPossible positions for symbols in definitionsf. := rhsdownvalue for ff/:fg.:=rhsdownvalue for fg/:f.,g,.:=rhsupvalue for gg/:f.,g.,.:=rhsupvalue for g TOPDefining ordinary and numerical valuesexpr = valuedefine a value to be used whenever possibleNexpr = valuedefine a value to be used for numerica

5、l approximationDefining numerical valuesthat depend on numerical precisionNexpr = valuedefine a numerical value to be used when defalut numerical precision is requestedNexpr,n=valuedefine a numerical value to be used when n-digit precision is requested TOPProtection for functionsUnprotectfremove protectionProtectfadd protection TOPFinding and setting values of symbolsDownValuesfgive the list of downvalues of fUpValuesfgive the list of upvalue