floating point verification using is?
bearophile
bearophileHUGS at lycos.com
Fri Dec 18 13:00:09 PST 2009
Steven Schveighoffer:
> That's great, but I'm trying to verify that my array building code
> correctly appends T.init. isNaN returns true no matter what the bit
> representation of nan is. I want to *specifically* compare bit
> representations of floating point numbers to ensure the code I'm writing
> is doing what I think it's doing.
I see :-) Let's try again (but next time please explain the full problem in your first post, and not a slice of it):
import std.c.stdio: printf;
bool isNanInit(T)(T f) if (is(T == double) || is(T == float)) {
union FPInt {
T f;
static if (is(T == float))
uint u;
static if (is(T == double))
ulong u;
}
static FPInt fnan, fx;
fx.f = f;
return fnan.u == fx.u;
}
void main() {
printf("%d\n", isNanInit(2.5));
float x;
printf("%d\n", isNanInit(x));
x = 2.5;
printf("%d\n", isNanInit(x));
}
Bye,
bearophile
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