On Monday, 11 June 2012 at 20:28:06 UTC, Era Scarecrow wrote:
On Monday, 11 June 2012 at 12:54:37 UTC, Adam D. Ruppe wrote:
a == b is probably done by the bits at runtime which match
because it is the same assignment.
But a == i_f might be propagated down there as 80 bit compared
to 32 bit and thus be just slightly different.
Unfortunately I used FloatRep and printed out the exponent and
fractions, and they were identical (false, 128, 4788187).
Besides, shouldn't the same types do a direct bit-wise copy?
Although re-reading your post it may make a little more sense...
So I added a couple more tests.. Strangely the exact same issue
is there while the rest aren't. The question then, is why the
32bit may be upgraded to an 80bit (if that indeed is happening)?
But that doesn't make sense since the 80bit can hold identically
anything the 32bit can hold and should still compare the same.
--
const float i_f = 3.14159265;
float a = i_f;
float b = i_f;
union fi {
float f;
ubyte[4] b;
}
fi c;
c.b = [219, 15, 73, 64]; //bit for bit of the same value.
float d = a; //float to float copy
assert(a==b); //passes (float/float copied from const)
assert(a==c.f); //passes (float/float union)
assert(b==d); //passes (float/float)
assert(a==i_f); //fails (float/const float)
