[Caml-list] Printing floating point numbers & precision

[mff <mff@research.att.com>]

Greetings,

I have a question regarding the printing of floating point numbers.  
Here's an example:

lt-mff: /usr/bin/ocaml
        Objective Caml version 3.07+2
# max_float;;
- : float = 1.79769313486231571e+30

# Printf.sprintf "%e" max_float;;
- : string = "1.797693e+308"

So using the default %e format to print a floating point number loses 11 
digits
of precision.    I could be more precise about the number of fractional 
digits:

# Printf.sprintf "%.17e" max_float;;
- : string = "1.79769313486231571e+308"

But this does not seem to work in general:

# Printf.sprintf "%.17e" 12345.1;;
- : string = "1.23451000000000004e+04"

I've combed the documentation to try to understand the relationship between
printing and precision (and accuracy!) but have come up empty handed.

Help is appreciated!
Thanks, Mary



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