JuliaLang/julia — pull request #1015 by aviks (2012-07-07 23:12:39+00:00)
Title: Conversion from Float64 to BigFloat should go via string

otherwise trash bits are converted. With existing code, the following behaviour is exhibited, which is incorrect.

```julia
julia> f=5.4
5.4

julia> BigFloat(f)
5.40000000000000035527

julia> BigFloat(f/2)
2.70000000000000017764

julia> BigFloat(f/4)
1.35000000000000008882

julia> BigFloat(string(f))
5.4

julia> BigFloat(string(f/2))
2.7

julia> BigFloat(string(f/4))
1.35

```