On Jan 14, 2012, at 1:23 PM, [email protected] wrote:
>
> That's a HORRIBLE idea! 3 decimal places are worse that IEEE. If it just a
> home accounting package, use doubles. If it is for the banking industry
> use a financial math library.
IEEE-754 is exactly what you don't want to use. Rounding errors in floats and
doubles will introduce errors into your calculations. Here's an example:
// some code to print a floating point number to a lot of decimal places
int main()
{
double f = .37;
printf("%.20f\n", f);
}
$ gcc -O -o foo foo.c
$ ./foo
0.36999999999999999556
Code snippet modified from:
http://www.theregister.co.uk/2006/08/12/floating_point_approximation/
As you can see, the internal representation of the number is not the number.
It's close, so very close, but "close" is the same as "wrong" in accounting.
--Rich P.
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