Hi Peter,
You are right, thanks for reporting these issues in the libquadmath
documentation. I am CC’ing the GCC mailing-list. Does the following patch seem
right?
diff --git a/libquadmath/libquadmath.texi b/libquadmath/libquadmath.texi
index dc2a9ff374b..ce4accf6421 100644
--- a/libquadmath/libquadmath.texi
+++ b/libquadmath/libquadmath.texi
@@ -118,15 +118,15 @@ The following mathematical constants of type
@code{__float128} are defined.
@table @asis
@item @code{M_Eq}: the constant e (Euler's number)
-@item @code{M_LOG2Eq}: binary logarithm of 2
-@item @code{M_LOG10Eq}: common, decimal logarithm of 2
+@item @code{M_LOG2Eq}: base 2 logarithm of e
+@item @code{M_LOG10Eq}: decimal (base 10) logarithm of e
@item @code{M_LN2q}: natural logarithm of 2
@item @code{M_LN10q}: natural logarithm of 10
@item @code{M_PIq}: pi
@item @code{M_PI_2q}: pi divided by two
@item @code{M_PI_4q}: pi divided by four
@item @code{M_1_PIq}: one over pi
-@item @code{M_2_PIq}: one over two pi
+@item @code{M_2_PIq}: two over pi
@item @code{M_2_SQRTPIq}: two over square root of pi
@item @code{M_SQRT2q}: square root of 2
@item @code{M_SQRT1_2q}: one over square root of 2
Regarding the naming of M_SQRT1_2q, it simply follows the traditional M_SQRT1_2
macro which, according to glibc doc: "These constants come from the Unix98
standard and were also available in 4.4BSD”. I agree with you that logic would
dictate M_1_SQRT2, but we simply follow the existing pattern there.
Best,
FX
> Many thanks for the 'quadmath.h' library, which is where I found this email
> address. I have addressed this email to you as the problem isn't a bug in
> GCC itself, it didn't seem right to try and coerce it into the bug report
> system, and I didn't know where else to start, but I appreciate that the
> problem is not yours, especially as the corresponding comments in
> 'quadmath.h' itself are correct. I'd be grateful if you could forward it to
> whoever is maintaining the Quad-Precision Math Library Manuals.
>
> Three of the constants are mis-labelled in the current (14.2) version of that
> Library Manual document (and in all the previous versions I've looked at) ,
> as follows:
>
> M_LOG2Eq: ) both are described as logarithms of 2, whereas they are
> logarithms of 'e'
> M_LOG10Eq: )
> ...
> M_2_PIq: described as "one over two pi", actually two over pi [2/pi]
>
> Additionally, whilst I realise that the two are mathematically equal, the
> generic 'M_numerator_denominatorq' naming format convention suggests that
> M_SQRT1_2q, described as "one over square root of 2", should better be
> labelled as "square root of (1/2)"; M_1_SQRT2q would be the name that
> corresponds to the original description. Is this a lacuna in the standard?
>
> Regards
>
> Peter Randall
