This question is related to this thread: http://d.puremagic.com/issues/show_bug.cgi?id=3632

Can you tell me why real.nan and real.init don't contain the same bit patterns?


import std.math: isIdentical;
void main() {
    assert(isIdentical(real.nan, real.init)); // this asserts
}

Bye and thank you,
bearophile

On Mon, 27 Jun 2011 16:41:14 -0400, bearophile wrote:

> This question is related to this thread: http://d.puremagic.com/issues/show_bug.cgi?id=3632
> 
> Can you tell me why real.nan and real.init don't contain the same bit patterns?
> 
> 
> import std.math: isIdentical;
> void main() {
>     assert(isIdentical(real.nan, real.init)); // this asserts
> }

real.init is a signaling NaN, real.nan is not.  I don't know if this is by design, but I suppose it may be:  You can "quiet" a signaling NaN by assigning real.nan to your variable.

  http://en.wikipedia.org/wiki/NaN#Signaling_NaN

-Lars

Lars T. Kyllingstad:

> real.init is a signaling NaN, real.nan is not.  I don't know if this is by design, but I suppose it may be:

Thank you for your probably correct hypothesis :-)

Bye,
bearophile