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1

I am trying to use a Module having "local functions", i.e., those which I need to define only inside this module.

So I tried this:

norm[p_] := Module[{
  fun1[p_] := p^2 + p - 1;
  fun2[p_] := p^3 - p^2 + p + 1
 },
 Max[fun1[p], fun2[p]]
];

The function is compiling, but when I try to evaluate it--say, I try:

norm[2]

Its giving me an error telling:

Module::lvsym: Local variable specification {fun1[p_]:=p^2+p-1;fun2[p_]:=p^3-p^2+p+1} contains fun1[p_]:=p^2+p-1;fun2[p_]:=p^3-p^2+p+1, which is not a symbol or an assignment to a symbol

How do we avoid this error? I want to give functions in the space between { ... }.

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That's some determined code formatting. :^) There is a much easier way: just select the entire block of code and click the { } button above the edit box to indent your code as a code block. Also see editing help. – Mr.Wizard♦ Feb 27 at 16:53
1  
Yes, or just press Ctrl+K – Ajasja Feb 27 at 17:01
2  
Mathematica is not a compiled language. The absence of messages at any particular point is not a good indication of correctness, since the evaluator assumes that what you're doing is meaningful until it arrives at something that's manifestly not. – Oleksandr R. Feb 27 at 17:10

1 Answer

up vote 11 down vote accepted

You cannot make definitions with patterns on the left-hand side in the first argument of a scoping construct (such as Module). You need do that in the body of the Module. You should also use a different symbol for the internal function parameter.

norm[x_] :=
  Module[{fun1, fun2},
    fun1[p_] := p^2 + p - 1;
    fun2[p_] := p^3 - p^2 + p + 1;
    Max[fun1[x], fun2[x]]
  ];
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