h.local

强大的数学工具包

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                           *   local   *
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        "local variable declaration"
        SYNTAX: local(X1,X2,...,Xn)

        X1,...,Xn are variables, n>=1.

        local can only be used at the beginnig of user-defined 
        functions.
        It creates local variables X1,...,Xn, which exist only
        while the function is evaluated.
        local(X1,...,Xn) is a stand-alone function which cannot be 
        used in expressions like X=local(X1,...,Xn) or 
        3+local(X1,...,Xn)-5.

        Global and local variables can be used in user-defined 
        functions. If a value is assigned to a variable which is 
        declared by local, then that local variable is used. If
        the variable is not declared by local in this function, 
        the value is assigned to the global variable.
        There is no overwrite-protection for local variables 
        in functions. At the end of a user-defined function,
        the local variables are deleted.
        
        
        Example 1: (correct)

                decl(f(a)=local(b,c)_if(a>0,b=fact(a)_c=a/b,)_return(c))


        Example 2: (incorrect)

                local(a1)
                
_ERR_NR_318


        Example 3: (incorrect)

                decl(f()=a=3_local(b)_b=a^2)
               
_ERR_NR_318