[Tutor] cube root

[Andre Engels]

On Mon, Jan 19, 2009 at 1:13 PM, spir <denis.spir at free.fr> wrote:
> Do you know any common algorithm to convert decimal (in the sense of fractional) decimals (in the sense of base 10 numbers) into binaries?
>
> 123.456                 --> 1111011.bbb...
> and/or
> 123456 * 10**(-3)       --> bbb... * 2**(-bbb...)
>
> How do python/C achieve that?

There's probably more efficient methods, but a simple method to
convert a decimal fraction to a binary would be the following
(untested):

def tobinary(n,precision=12)
    # n is a number between 0 and 1 that should be converted,
precision is the number of binary digits to use.
    assert 0.0 <= n < 1.0
    outcome = "0."
    compare = 0.5
    for i in xrange(precision):
        if n > compare:
            outcome += "1"
            n -= compare
            if n == 0.0: break
        else:
            outcome += "0"
        compare /= 2
    return outcome

-- 
André Engels, andreengels at gmail.com