On Sat, 07 Feb 2015 21:33:46 +, Kenny wrote:
The above code snippet works correctly when I use LDC compiler (it finds
expected 'f' value and prints it to console). I'm wondering is it a bug
in DMD?
nope, this is a bug in your code. compiler (by the specs) is free to
perform intermediate
nope, this is a bug in your code. compiler (by the specs) is
free to
perform intermediate calculations with any precision that is
not lower
than a highest used type (i.e. not lower that `float`'s one for
`while`
condition (`f + eps != f`). it may be even infinite precision,
so your
code may
On Sun, 08 Feb 2015 09:05:30 +, Kenny wrote:
Thanks, it's clear now. I still have one question in the above post, I
would appreciate if you check it too.
i've seen that, but i don't know the answer, sorry. here we have to
summon Walter to explain what his intentions was, how it should
For example, according to IEEE-754 specification if we work
with 32bit floating point numbers (floats in D) then the
following pseudo code prints 'Works'.
F32 f = 16777216.0f;
F32 f2 = f + 0.1f;
if is_the_same_binary_presentation(f, f2)
Print(Works);
As I understand D does not guarantee
On Sunday, 8 February 2015 at 09:19:08 UTC, Kenny wrote:
For example, according to IEEE-754 specification if we work
with 32bit floating point numbers (floats in D) then the
following pseudo code prints 'Works'.
F32 f = 16777216.0f;
F32 f2 = f + 0.1f;
if is_the_same_binary_presentation(f, f2)
i think you are mixing two things here. IEEE doesn't specify
which
internal representation compilers should use, it only specifies
the
results for chosen representation. so if D specs states that
`float`
calculations are always performing with `float` precision (and
specs
aren't), your sample
There is no right or wrong when you compare floating point
values for equality (and inequality) unless those values can be
represented exactly in the machine. 1.0 is famously not
representable exactly. (It is similar to how 1/3 cannot be
represented in the decimal system.)
Here I tested one
On Sun, 08 Feb 2015 09:19:06 +, Kenny wrote:
I asked more about this case:
float f = 16777216.0f;
if (f == f + 1.0f)
writeln(Works);
Although all operands are 32bit FP the result is not guaranteed to be
equal to the result for FP32 computations as specified by IEEE-754.
i think you
Also note that denormal numbers is an issue, e.g. D assumes that
they are always supported, I think. Which frequently is not the
case...
And sory for the typos, cannot find edit functionality here..
On Saturday, 7 February 2015 at 21:33:51 UTC, Kenny wrote:
The above code snippet works correctly when I use LDC compiler
(it finds expected 'f' value and prints it to console). I'm
wondering is it a bug in DMD?
p.s. the final code used by both compilers:
import std.stdio;
import std.conv;
On Saturday, 7 February 2015 at 23:06:15 UTC, anonymous wrote:
On Saturday, 7 February 2015 at 22:46:56 UTC, Ali Çehreli wrote:
1.0 is famously not representable exactly.
1.0 is representable exactly, though.
I think he meant 0.1 :-)
On 02/07/2015 01:33 PM, Kenny wrote:
The above code snippet works correctly when I use LDC compiler (it finds
expected 'f' value and prints it to console). I'm wondering is it a bug
in DMD?
p.s. the final code used by both compilers:
import std.stdio;
import std.conv;
int main(string[] argv)
To answer your other question, there is no Edit because this is a
newsgroup (see NNTP). The forum interface is supposed to be a
convenience but it hides that fact.
On 02/07/2015 01:33 PM, Kenny wrote:
The above code snippet works correctly
There is no right or wrong when you compare
On Saturday, 7 February 2015 at 16:06:14 UTC, Kenny wrote:
Hi, D community!
I have this program:
import std.stdio;
import std.conv;
int main(string[] argv)
{
float eps = 1.0f;
float f = 0.0f;
while (f + eps != f)
f += 1.0f;
writeln(eps = ~ to!string(eps) ~
On Saturday, 7 February 2015 at 22:46:56 UTC, Ali Çehreli wrote:
1.0 is famously not representable exactly.
1.0 is representable exactly, though.
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