.SH RETURN VALUE
On success, these functions return the natural logarithm of
.IR x .
-
+.PP
If
.I x
is a NaN,
a NaN is returned.
-
+.PP
If
.I x
is 1, the result is +0.
-
+.PP
If
.I x
is positive infinity,
positive infinity is returned.
-
+.PP
If
.I x
is zero,
or
.RB - HUGE_VALL ,
respectively.
-
+.PP
If
.I x
is negative (including negative infinity), then
.TE
.SH CONFORMING TO
C99, POSIX.1-2001, POSIX.1-2008.
-
+.PP
The variant returning
.I double
also conforms to