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We can compute the logistic map using finite, but
arbitrarily large binary expansions. Notice that this is
different from multiple precision, as the size of a multiple-precision
number is fixed in advance. This is
- 1.
- reliable, but
- 2.
- unfeasible in terms of time and space consumption.
For n > 10, the computation of fn(x0) takes more than I
was patient to wait for. Thus, this is even worse than rational
arithmetic. It is easy to see why this is the case. If x has a
binary expansion with n digits, then 1-x has often n digits as
well. But if x and y have m and n digits then xy has mndigits. Thus,
fn(x0) has approximately 2n m digits if x0has m digits.
Martin Escardo
2000-10-02