On Wednesday, 20 October 2010 at 10:32:06 UTC, Lars T.
Kyllingstad wrote:
(This message was originally meant for the Phobos mailing list,
but for some reason I am currently unable to send messages to
it*. Anyway, it's probably worth making others aware of this
as well.)
In my code, and in unittests in particular, I use
std.math.approxEqual() a lot to check the results of various
computations. If I expect my result to be correct to within
ten significant digits, say, I'd write
assert (approxEqual(result, expected, 1e-10));
Since results often span several orders of magnitude, I usually
don't care about the absolute error, so I just leave it
unspecified. So far, so good, right?
NO!
I just discovered today that the default value for
approxEqual's default absolute tolerance is 1e-5, and not zero
as one would expect. This means that the following, quite
unexpectedly, succeeds:
assert (approxEqual(1e-10, 1e-20, 0.1));
This seems completely illogical to me, and I think it should be
fixed ASAP. Any objections?
Changing it to zero turned up fifteen failing unittests in
SciD. :(
-Lars
* Regarding the mailing list problem, Thunderbird is giving me
the following message:
RCPT TO <pho...@puremagic.com> failed:
<pho...@puremagic.com>: Recipient address rejected:
User unknown in relay recipient table
Are anyone else on the lists seeing this, or is the problem
with my mail server?
Just a hint don't use approxEqual() to compare GUI object
coordinates >!<
