[glibc] manual: Clarify return value of cbrt(3)

[Adhemerval Zanella <azanella@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e01b3b86e821e1132da76ce79ebb301033141e6d

commit e01b3b86e821e1132da76ce79ebb301033141e6d
Author: Alejandro Colomar <alx@kernel.org>
Date:   Sun Mar 31 22:38:48 2024 +0200

    manual: Clarify return value of cbrt(3)
    
    Link: <https://lore.kernel.org/linux-man/ZeYKUOKYS7G90SaV@debian/T/#mff0ab388000c6afdb5e5162804d4a0073de481de>
    Reported-by: Morten Welinder <mwelinder@gmail.com>
    Cowritten-by: Morten Welinder <mwelinder@gmail.com>
    Cc: Adhemerval Zanella Netto <adhemerval.zanella@linaro.org>
    Cc: Vincent Lefevre <vincent@vinc17.net>
    Cc: DJ Delorie <dj@redhat.com>
    Cc: Paul Zimmermann <Paul.Zimmermann@inria.fr>
    Cc: Andreas Schwab <schwab@linux-m68k.org>
    Signed-off-by: Alejandro Colomar <alx@kernel.org>
    Reviewed-by: DJ Delorie <dj@redhat.com>

Diff:
---
 manual/math.texi | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/manual/math.texi b/manual/math.texi
index 79bf3a1401..dfb685a71e 100644
--- a/manual/math.texi
+++ b/manual/math.texi
@@ -700,8 +700,12 @@ Mathematically, it should return a complex number.
 @standardsx{cbrtfN, TS 18661-3:2015, math.h}
 @standardsx{cbrtfNx, TS 18661-3:2015, math.h}
 @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
-These functions return the cube root of @var{x}.  They cannot
-fail; every representable real value has a representable real cube root.
+These functions return the cube root of @var{x}.
+They cannot fail;
+every representable real value
+has a real cube root,
+and rounding it to a representable value
+never causes overflow nor underflow.
 @end deftypefun
 
 @deftypefun double hypot (double @var{x}, double @var{y})