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Re: Code to translate to negative base...

• To: mathgroup at smc.vnet.net
• Subject: [mg64543] Re: Code to translate to negative base...
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Wed, 22 Feb 2006 05:58:26 -0500 (EST)
• Organization: The University of Western Australia
• References: <dte2au$rie$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

In article <dte2au$rie$1 at smc.vnet.net>,
 Richard Palmer <mapsinc at bellatlantic.net> wrote:

> ... Does anyone have code to translate to a negative base?  Ideally the code
> would work like RealDigits; except that the second argument (base) could be
> negative.

See 
 
  http://library.wolfram.com/conferences/devconf99/challenge/winners.nb

for extension of IntegerDigits to base -2. Extension to negative integer 
base is straightforward:

  integerDigits[0, n_Integer /; n < 0] := {0}

  integerDigits[i_, n_Integer /; n < 0] := Rest @ Reverse @ 
     Mod[NestWhileList[(# - Mod[#, -n])/n & , i, # != 0 & ], -n]

Now, you just need to extend this to handle real numbers ...

Cheers,
Paul

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Paul Abbott                                      Phone:  61 8 6488 2734
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