Comparing two notions of computable number

From: Axel Boldt (axelboldt_at_yahoo.com)
Date: 02/24/04


Date: 24 Feb 2004 07:26:23 -0800

In http://wikipedia.org/wiki/Computable_number two notions of
computable number are given:

1) a real number a is computable iff there exists a Turing machine
which for given rational number eps produces a rational approximation
r such that |a-r|<eps

2) a real number a is computable iff there exists a Turing machine
which for given natural number n produces the n-th decimal digit of a

Definition 2 seems to be (equivalent to) Turing's original definition.
Clearly, every 2-computable number is 1-computable. Is the converse
also true?

Thanks,
  Axel



Relevant Pages

  • Re: Comparing two notions of computable number
    ... axelboldt@yahoo.com (Axel Boldt) wrote ... > 1) a real number a is computable iff there exists a Turing machine ... There is no general algorithm which transforms eps-approximating ...
    (comp.theory)
  • Re: Comparing two notions of computable number
    ... > 1) a real number a is computable iff there exists a Turing machine ... > which for given rational number eps produces a rational approximation ...
    (comp.theory)