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Re: function's local constants interdependence

• To: mathgroup at smc.vnet.net
• Subject: [mg69613] Re: function's local constants interdependence
• From: dimmechan at yahoo.com
• Date: Sun, 17 Sep 2006 22:45:43 -0400 (EDT)
• References: <eejaql$40m$1@smc.vnet.net>

Hi Igor.

You should use Block.

Clear["Global*"]
ff[x_, y_] := Block[{a = x, b = 2*a}, {a, b}]
ff[x, y]
{x, 2*x}

You can also execute the following commands to see the difference.

Clear["Global*"]
ff[x_, y_] := With[{a = x, b = 2*a}, {a, b}]
Trace[ff[x, y], TraceOriginal -> True]

Clear["Global*"]
ff[x_, y_] := Block[{a = x, b = 2*a}, {a, b}]
Trace[ff[x, y], TraceOriginal -> True]

Clear["Global*"]
ff[x_, y_] := Module[{a = x, b = 2*a}, {a, b}]
Trace[ff[x, y], TraceOriginal -> True]

Regards
Dimitris Anagnostou

Î?/Î? rych έγÏ?αÏ?ε:
> Could someone please help me find a decent way to have local constants
> defined using one another in order?
> Simple "With[" doesn't work:
>
> Clear[a,b,x,y]
> ff[x_,y_]:=With[{a=x, b=2*a},{a,b}]
> ff[x,y]
> > {x,2 a}
>
> where I'd like it be >{x, 2 x}. I suspect it would work with "Module["
> but I especially wanted them to be constants.
>
> Do I have to nest With[ ? Or is there a prettier way?
> Thanks
> Igor