h.decl

强大的数学工具包

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                           *    decl   *
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        "declaration of user-defined functions"
        SYNTAX: decl(F1,F2,...,Fn)
        SYNTAX: Fi: fct(p1,...,pm)=seq
                    fct()=seq

        F1,...,Fn are functions of the syntax described above, n>=1.
        fct is the name of the user-defined function, which may also 
        be an array. p1,...,pm are variables, which are the 
        parameters of fct, m>=1.
        seq is a sequence of several expressions, separated by '_' or 
        ';'. If an expression ends with '_', its output is displayed,
        if it ends with ';', its output is suppressed. The sequence
        must not be empty.

        decl assigns the function Fi to the name fct. At the
        moment of declaration, seq is not evaluated.

        If local variables are used, the function local must be 
        at the beginning of the user-defined function (see "?local").
        The sequence may contain the function return (see "?return").

        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.

        Parameters are handled like local variables.
        The parameters and variables are not declared with
        a specification of the type.

        The user-defined function is evaluated by the call
        fct(A1,...,Am), fct(), X=fct(A1,...,Am) or X=fct(), 
        respectively, where A1,...,Am are any simcalc expressions, 
        whose values are assigned to p1,...,pm.

        If a function is terminated by return(A), where A is a 
        simcalc expression, the function returns the value of A.
        Otherwise, no value is returned.
        
        
        Example 1: (correct)

                decl(ec[1](a)=local(E)_if(a==3,print("singular")_return(-1),)_E=EC(a,0,1,0,0);j=jinv(E)_tors(E,3)_return(rk(E)))



        Example 2: (Evaluation)

                for(a=0,10,ec[1](a))


        Example 3: (correct)

                decl(f1(a)=return(f2(a,a-1)), f2(a,b)=return(b*f3(a)),
                     f3(c)=return(c!))